Toxic timbern idea. Where Bernard is in the midst of the Children of Dionysus and his depression, and Tim has grown obsessed with him from the shadows. This is before Bernard had the idea to reach out on his own, so they're not reconnected. Tim finds Bernard on social media, and instead of reaching out himself, begins to grow obsessed. With Bernard's new life, how he moved on from Louis Grieve, etc. So obsessed that he begins to stalk him.
It's gradual, of course. It starts with Tim feeling so guilty that he left Bernard without a word so he doesn't feel confident to reach out. Then, the little check-ins on an old friend become frequent. Become every day. Become every few hours. Become not being satiated by social media anymore, so he turns to real life. This grows into following him as Red Robin during the nights to make sure he's safe. Then it's watching him walk home from University to make sure he's safe. Then it's watching him walk anywhere to make sure he's safe. It's peering into windows to know who he talks to. It's hacking into security and street cameras. It's bugging his room and his house. It's tracking his online behavior and devices, just to 'check in'.
Bernard notices, obviously. He sees the cameras placed discreetly. He notices the sheer lack of crime that he'd run into- somehow- in Gotham. I mean, it's hard to ignore the flash of a camera coming from your window in the pitch dark of night.
But he isn't scared. No, not at all.
Because whoever is doing this is helping him. Is protecting him from anything that might come after him- and is seeing him in ways he's never been before. To Bernard, this is the most utter act of devotion.
He isn't scared. Frankly, he's charmed.
His heart races when he catches a glimpse of a bugged bookshelf or cabinet. He gets butterflies in his stomach when he feels eyes watching him wherever he goes. He can't help but kick his feet when he finds evidence of tampering on his phone, because this stalker isn't as slick as they think.
Then he starts getting photos. Captures of himself left under his doormat, on his pillow, on his window sill. Flowers left on his fire escape and in his kitchen. Things that he'd wanted to buy and even coffee on the counter. And he feels so, so loved.
He begins to dig on his own. He starts to investigate their identity, playing stupid just well enough to sneak glimpses. To see black hair and pale skin, always hidden by a dark hoodie. To see- just once- blue eyes peering back at him in the dead of night, before he never saw them again. And he revels in it all.
He looks back at them. When he finds a gift, he says 'thank you' to the empty room because he knows it's not really empty. He teases with just enough plausible deniability that makes Tim question and grow even more obsessed because 'is he doing it on purpose? Is it just a coincidence?' he has to know.
Tim starts growing more intentional. He starts leaving little notes, little hearts and messages. Then, next time he breaks in to steal another thing of Bernard's, he finds a note for him. He finds Bernard's adorable handwriting with words of love for him to find.
From there, they're completely mutually devoted. Bernard is just as entranced with the figure watching him as the figure is with him. And he devotes himself wholly.
Bernard, who is just crazy enough to start referring to his stalker as his boyfriend, starts telling people he's taken.
Tim, who's now scouring every inch of Bernard's life, history, and honestly driving himself insane with jealousy and rage in searching for this 'boyfriend'. Because how dare another man think they have the right to Bernard.