I have another NottPott idea rolling through my head so I figured I'd post it here to save it and whatnot since I don't want to lose it!
I'm thinking of calling it Hopelessly Devoted!
I'm a fan of darker tropes but haven't written one and kind of wanted to try my hand at it. Essentially the idea is that Theo meets Harry on the train to Hogwarts as Harry got there early because the Dursleys wanted to get him away as soon as possible and Harry luckily caught a family passing that had similar items like him and he watched them vanish into the wall.
He followed as sneakily as he could as he did not want to be noticed after learning he was famous and luckily was not noticed so he found a compartment early on and got settled after wrestling with his trunk longer than he'd like to admit. Theo is a very punctual person as is his dad so they arrive early as well. After saying his goodbyes to his parents he goes in search of a compartment and curiously feels his magic leading him to one towards the back. He trusts his magic so he follows. He's not shocked to see someone in the compartment but he is shocked by the beautiful green eyes that meet his once he steps into the compartment.
My idea is a yandere Theo which isn't a new idea but like I said I want to try my hand at it. My thought is that it's a Nott family thing where anyone born in the family isn't really interested in much until they find their perfect person. Not so much that they don't feel any emotion until they meet their fated one but more so they do feel emotions they are just somewhat dull and not much captures their attention until they meet their fated one. The one whose magic calls to them.
Harry is of course that person to Theo and he's one of the few to meet his fated one so early! He's ecstatic. To the point he immediately proposes. I mean legit on one knee, hand held out to Harry and one hand over his heart. Harry is caught off guard but thinks Theo is silly. He doesn't really know what Theo is talking about, what with him being extremely sheltered thanks to the Dursleys. Harry is a little more naive than in canon when it comes to information, including relationships. So when Theo asks him to be his betrothed he latches on because he wants a friend and Theo seems to like him which never happened before so he says yes. Theo gives him a ring of his for some odd reason, I headcanon this Theo to be obsessed with jewelry because of his mom. The ring is one of the many portkeys back home he has because his parents are so paranoid about his safety so he doesn't think twice about giving it to Harry.
Harry is amazed when it automatically resizes to fit him and since Theo is his friend and betrothed (maybe that means best friend in the wizarding world?), Harry happily asks how it does that and Theo immediately begins talking about runes and when he sees Harry is still interested and even asks him good questions, Theo falls more. He's basically patting himself on the back for a good fated one.
No one bothers them in the back because it's known that the older students claim it and when some older kids spy the two first years excitedly talking to each other they don't have the heart to tell them to move. Theo shares his packed lunch that his mother made with Harry who is so grateful that he hugs Theo tightly. Theo takes the opportunity to feed things to Harry because "It's what my mother and father do for each other and they were betrothed so it's fine." When the trolley witch comes by, Harry does buy sweets but not everything because Theo is there and gives his recommendations.
Harry returns the favor of Theo feeding him by feeding him sweets.
It's because of this whole journey that once they get to Hogwarts and Theo is sorted into Slytherin that Harry follows. Sure Hagrid said Slytherin was bad news but how bad could it be if that's where Theo goes? He's so happy to follow his friend that he doesn't even notice the stunned silence that follows. He's oblivious to much going on around him because he and Theo are talking once more and stunned silence happens once more because the two don't notice that everyone is basically watching them and Theo just fed Harry some food from his plate. And then Harry did it back.
Baffled. Everyone is baffled!
Malfoy was going to make a comment but he's so disturbed by the smile Theo has that he merely settles on talking with Pansy and doingnhis best not to look at Theo and Harry.(Nott never smiles! Never! It's unnerving!)
No one really knows what to say so they just decide to ignore the two but not Blaise, he's enjoying the tension. So he promptly introduces himself and everyone else at the Slytherin table is trying their best not to gawk at him. Harry happily shakes Blaise's hand while introducing himself while Theo merely clasps the boy's arm once and smugly introduces himself as "Theodorus Erik Nicomedes Nott. Harry's betrothed." And Harry happily shows off his ring.
Several older snakes choke on their food or drink.
Dinner passes in that fashion and once they are in the dorms and given their welcome speech and Snape comes in to give his own, Theo is ready to throttle the old man for all his pointed comments and sneers and glares at Harry who loses his smile and silently looks at the floor while standing so stiffly. Theo vows revenge. When they are sent to their rooms, thankfully Theo and Harry are sharing a dorm with Zabini, Harry is still quiet.
It takes a while for him to come back to Theo and Theo vows that the revenge will be worse than he was originally planning. Then they're getting ready for bed and Theo spots the...rags his beloved lays out on his bed and immediately lights them on fire. They are most definitely not worthy of touching his beloved's skin! Harry is understandably upset but Theo immediately grabs a set of his pyjamas and hands them to Harry.
It takes a while before Harry begrudgingly takes the offered pyjamas and goes to change. When he comes out, the pyjamas are bigger on Harry than Theo anticipated but he thinks Harry looks adorable. He somehow even convinced Harry to sleep in Theo's bed with him because "My mother and father do it and they were betrothed so it's fine." (His excuse but it's not an excuse because he actually believes it 💀)
The headboy sees this when he goes to check on them but just marks them as being there and goes on his merry way. He's almost done with school anyway and the boys aren't doing anything technically wrong so he lets them be.
Theo is so very protective of Harry that the other Slytherins catch on fast. They of course tried to hex Harry or confront and bully him but they quickly realized why that was not going to fly. In the first week alone, Theo sent eight upper classmates and Crabb, Goyle, and Pansy to the infirmary. One upperclassman decided to go for Theo instead and he was also sent to the hospital wing by Harry. It's also during that first week that Theo bumps Snape up his enemy list for how he treated Harry during their first potions class. Ronald Weasley is also on the list for how he tries to make Harry his friend but also how he yells at Harry for "betraying" them all. Snape is the bigger threat.
It's not until their second month at school that Theo enacts his revenge. He had been following Snape for days with Harry and they realized that Snape kept going to the third floor which was off limits and that he also confronted Quirrell a lot. Theo decided on a karmic curse. Harry believed it would be mild but Theo knew how nasty the older man was to everyone but especially Harry and he knew whatever came to be would be big. Either permanent injury or disfigurement or death. Theo is fine with either.
They perform the ritual to complete the curse of Halloween/Samhain as Theo explained its significance as a Sabbat and how powerful it was. Harry asked Theo to help him honor his parents since he learned that was the day his parents passed and Theo was all too happy to help. It seemed symbolic.
After performing the curse in an abandoned classroom on the third floor they decided to skip the feast and just go to the library. On their way down though, they heard crying and Harry of course followed it. When they realized it was the girls' restroom Theo refused to go in as it was not proper so Harry spoke from outside it. It's as Harry is coaxing out Granger that Theo smells it.
He turns and sees a Merlin-damned-Troll lumbering towards them! He starts yelling at Granger to get out because there's a troll and Harry looks scared. But Harry, his beloved, is a courageous idiot and runs into the girls' bathroom and grabs Hermione. The only reason Theo didn't run despite the troll getting closer and closer is because he refuses to leave Harry.
Next thing they know, they are running for their lives and yelling for help. Snape rounds the corner and doesn't seem to notice the troll just yet as he seems to be taking sick pleasure 6 yelling at Harry and grabbing his wrist so he can't run as he takes points (from Gryffindor....) the children are yelling at him about the troll but they barely manage to yank Harry away from Snape before the trolls club hits the man.
He's not dead. (Sadly)
Of course Harry and Hermione try to distract the troll from getting another hit in and that's finally when the other teachers arrive to see Harry, brave foolish Harry, yell out lumos and basically blind everyone but including the troll and then all three kids start to try and drag Snape away. (They don't see the other teachers. Theo isn't really trying.)
The troll dropped the club but was getting to close to them and Theo would never let Harry get hurt so he wingardium leviosas the club up and aims it true high above the troll and releases the spell. He didn't think he had dropped it from that high but once the trolls skull was crushed in he guessed it was higher than he thought.
There's no lying from Hermione. Theo and Harry explain how Harry didn't want to go to the feast because he found out today was the day his parents passed and Theo didn't want him to be alone so they simply relaxed in an unused room and when they decided to leave they heard Hermione. Theo greatly enjoyed explaining that things could have been avoided if not for Snape. The only one who looked sorry for the man was Dumbledore. McGonagall gave them points and that was that.
Professor Vector took over as their head of house as she was a former Slytherin. Snape wouldn't be back to work for the rest of the year due to his injuries. The board of governors appointed Theo's mom as the interim potions professor which Theo was very pleased with. He could finally introduce his beloved to his mom! Letters didn't do justice!
The rest of the year passes well. Hermione became Harry's friend and Theo's begrudging acquaintance. They somehow stop Hagrid from trying to hatch and raise a dragon. Theo gets his mom and Professor Vector to sign a permission slip for him and Harry to self-study defense due to all the headaches Harry got in the class. Harry got an invisibility cloak for Christmas that had Theo suspicious since Harry got to come with Theo and his mom home for Christmas since his mom had access to the floo and Vector gave her permission as Harry's head of house.
Quirrel went missing which was weird and Dumbledore kept trying to get Harry into a meeting alone but Theo made sure Professor Vector accompanied him each time. And each time she got progressively more irritated as each meeting was not about school at all and she got pissed when it seemed like Dumbledore was disappointed that Harry didn't try to stop Quirrel.
School year ends and Harry has to go back home as he hasn't told anyone how the Dursleys are not even to Theo because he was so distracted by magic and Hogwarts and Theo. But when he promised to write and then didn't, Theo got worried and demanded his father track the ring he gave Harry. His father is flabbergasted and appalled that his son gave away one of their family rings (also that his fated one was Harry-freaking-Potter) but does it as Theo's and his mom's insistence.
They are the ones who find Harry with the bars on his windows and when they get inside the house, they see the cat flap and locks. His mom is rightfully enraged and even his dad looks sick at the sight. Instead of breaking Harry out right away like they want to, once Harry explained about the notice he got for underage magic, Theo's mom went and summoned Amelia Bones who brought aurors and magical child protective services. Theo's dad, Erik, did bind the Dursleys though, and let Harry out of the room. Theo cried for the first time since he was a babe at the sight of his beloved so skinny and hurt. He could smell the blood and felt it when he ran and hugged Harry to him. Theia immediately set to heal him while the aurors arrived.
They were appalled that this is how they found the Boy-Who-Lived. One of the child services members tried to take Harry but Theo snarled and yelled that Harry was his betrothed and they had a right to take care of him according to ancient law.
Stunned silence. Even from Erik.
Harry shakily shows off his ring and the silence is stunned once more.
Harry gets to go with Theo as he heals and an investigation is launched.
That's where I'll leave it but I have so many ideas for this au!!!! I think I'll post headcanons for it and By Any Other Name!!! But I won't start writing it until BAON is finished or halfway! But asks are always open if you're curious!