So with the new Friend information basically confirming that Friend and Eram are two separate entities (finally, I did not care for that theory) I think a lot of the stuff that has been attributed to Friend has been Eram. While there are obvious questions;
If Friend isn't Mike, does that mean Eram is Mike? (Maybe.)
If Friend isn't the mysterious someone, Does that mean it's Eram? (Also Maybe.)
At a baseline we should establish the concrete information about Eram.
[WHAT WE KNOW FOR CERTAIN]
Eram's only onscreen appearance is in Chapter 3's sword route. They appear for the fight at the end of the route and are implied to be the one speaking to the player/kris throughout the route in the caves. However due to FRIEND appearing in these caves it is also plausible that FRIEND is the one saying those things prior to Eram, or at least delivering the message.
Eram is directly tied to Kris and their trauma, having a rather intimate view of their Psyche. They appear behind the red horn headband door, which directly ties to Kris's Headband which we currently do not know the location of. (The previous theory was that Ralsei was the headband but after Ch5 it's more likely that Ralsei is not a normal Darkner but is something more akin to a Plantner or something entirely unique.) Eram is stated to be 'wearing' the Shadow Mantle, so it's unlikely their avatar in the game is an accurate repersentation of their real appearence.
Eram uses Fire magic, Bombs, and summons FRIENDLINGS. All of this directly ties them to cats through information we now have in Chapter 5. Pink's body (I'll just call her Mew Mew for simplicity) states she used to know someone who liked Cats and had a whole hunting pack of cats. Though not directly stated, the implication seems to tie this Cat-Lover to the Mysterious Someone who contacted Jevil, Spamton, (Maybe Gerson), and Mew Mew.
Now the biggest part; Eram is fully meta aware. So far very few characters have true meta awareness with the only other ones we know of so far being; Gaster (No explaination needed), Friend (Modifies the geometry of levels), and the Knight (Ignores Flowery's fake stats, can interact with damage numbers). Eram showcases knowledge of the weirdroute (though arguably this is simply in relation to the sword route's version of it) and they are able to directly damage Kris & the Soul through the video game, something no other entity was shown being able to do.
Beyond that we have some Meta Knowledge that isn't directly in the gameplay. Eram's fandom name (Eram) derives from the soundtrack that plays while they speak to Kris before the boss fight. Their battle theme is called 'Burning Eyes' which directly parallels Ice-E from the spamton sweepstakes*. This directly ties Eram to Dess due to her being the one to burn the P'e'zza box. Furthermore Eram is tied to whatever is going on with roots; This is due to one of the soundtracks in the sword route being named 'Bit Roots'. Notably Roots is also present in Chapter 2, being called 'Digital Roots'. This further ties Eram to Spamton as Spamton is already related to FRIEND for reasons I doubt I need to explain.
*It is VERY important to note that the Sweepstakes are NOT directly canon. They PARALLEL canon, but the events in the Sweepstakes did not literally happen in universe.
The most important part though; ERAM KNOWS ABOUT THE SHADOW CRYSTALS. The only other character who seems to fully comprehend the Shadow Crystals and actually talks about them is Seam (another cat). This instantly ties them to the other secret bosses just by the fact they know about the crystals.
All this was necessary to establish because Toby is a very intentional writer. He is known for putting double meanings throughout his games. I suspect Roots is one of these double meanings;
1. Roots refers to Kris's historical roots, their past. It refers to their mental issues and their traumatic past in relation to Dess.
2. (Assuming Ralsei Plantner theory*) The roots are also literal, being a web of roots that stretch beneath the entire town, connecting everything.
*While not entirely relevant here the theory is that Ralsei is a Plantner version of the trees around hometown, being a colony organism similar to real life's Pando. The reason he can travel between dark worlds is because his roots stretch beneath the town through the darkness, allowing him to be anywhere.
Eram is connected to Kris's trauma. If not literally then at a bare minimum metaphorically. They directly parallel the Headband due to the door. Friend is implied to be apart of Kris's trauma and Eram commands a pack of them in their boss fight. Eram mocks Kris's violent impulses and intrusive thoughts. Kris consistently gets compared to a dog. Eram consistently gets associated with cats.
With every secret boss tying into one or more of the hero's insecurities and issues* it should go without saying that Eram is important to Kris's story. Their connections here are important in that they're necessary for Kris to grow in some way.
*Jevil = Susie's disregard of the dark world and her violent tendencies & The player's belief that they're free from the world's narrative
*Spamton = Kris being literally controlled like a puppet & Ralsei being a puppet of the narrative
*Gerson = Susie's insecurities and lack of mentorship
*Mew Mew = The Soul & Kris's relationship & Maybe Ralsei Transgender?
Another thing of note is how much Aqua parallels Kris & Eram (and also Jevil). Due to Asgore's flashback we know Kris used to have a Patience soul. Either that soul changed and became the current one, or that Patience soul went missing. Regardless Aqua is the only soul flower that has more than one primary color, being Blue (Patience), Red (Determination/Ball Game), and Black?
Aqua is impulsive, not very smart, and heavily associated with fun through violence. All of which are traits Eram mocks Kris for having at the beginning of the fight. While not great evidence in and of itself, I think it's notable that Aqua clearly has the oldest sprite out of all the flowers. Her design is evidently important enough that Toby made it himself and it suck around for however long. I think it's safe to say this design is important. Notably her hair resembles the shape of Eram; Aligning Aqua's hair tufts to Eram's fangs we get the following.
I think this is important because Aqua is meant to parallel a younger Kris. Eram also parallels Kris. While I'll get into it deeper soon, it's notable that young Kris had a special object (The horn headband) they have since lost, being an object which channels their now lost hope of being a monster. If that object were to become a darkner then it would likely carry some twisted feelings towards Kris both because it understands their mentality and because it was abandoned (similar to the resentment King feels for being abandoned.)
Eram is so heavily associated with the weird route because it's the route that exemplifies their philosophy. Violence makes you stronger in this world and by being violent and through breaking Noelle mentally and emotionally, you become stronger.
Eram is the Headband.
This is the entire basis of the rest of the theory. They're so heavily tied to Kris's Trauma and the Headband I find it very unlikely they're not related. Even if the headband is just armor Eram wears or something. Eram is basically Kris's opposite. Kris is a dog person, Eram is a cat person. Kris was traumatized by Friend, Eram commands Friends.
Timeline wise I believe events carried out like so;
1. Kris & Dess nonsense happens its a whole different theory so staying brief. this included Friend and the Shelter, somehow.
2. Kris is traumatized by Friend, accidently leaves the Horn Headband behind in the Shelter, and goes into therapy.
3. While Kris moves on with their life the Headband is left in the dark for years, never truly growing as a person, only really knowing a life as child Kris's ideal self. A strong monster.
4. During this time in the Shelter the headband (now Eram or whatever their name, maybe Kris's deadname or something really fucked up like that) they end up joining up with the Shelter crew and thus Gaster. They also gain command over the FRIEND Hoard. (Notably the FRIENDs seem to hate Boredom as Mew Mew implies, so Eram wanting fun is another FRIEND parallel)
5. Eram's twisted obsession with Kris grows up until right before the events of the game itself. During this time the mantle drives Jevil insane and give him a shadow crystal (perhaps this crystal was formed from Kris's own lost dream, which would explain why Eram had it.)
6. The events of the game playout; Eram is the benefactor and ends up sicking the Friends in Spamton after he breaks their deal (the shadow crystal in ch2 is Mettaton's lost dream). Eram appears in ch3 to mock Kris and force them to fight for the mantle. This is their way of making Kris more like them, strong through violence. Eram plants the crystal in Gerson's desk (Alvin's lost dream) but doesn't have time to do anything else. They interact with Mew Mew (The shadow crystal is Pink's lost dream, but that dream is now realized.)
So heres what I think Eram's goal and role is;
Eram & Kris is paralleling Flowery & Ralsei's Mentorship, just a more twisted and fucked up version of it. Flowery continually ragebaited Ralsei and prodded him to force Ralsei into growing more independent and assertive so that he would question the prophecy and his action. It made Ralsei stronger through adversity. Eram wants the same for Kris, but is far less nice about it. Eram believes the only way for Kris to get stronger and to become their ideal self is through VIOLENT adversity. The core of the battle system between fighting and sparing is simple; 'The bonds you break may make you stronger.' They certainly do. Each shadow boss gives the group powerful items and shadow crystals which can be used to make something pretty strong. Eram's goal is to make Kris stronger by forcing them to embrace their own philosophy.
I think this is going to manifest in an eventual Eram fight where Eram's goal isn't to win, it's to die (though they'll certainly go 100% all out trying to kill the party they don't seem like the type to go easy). Eram wants Kris to break the bonds they had with them to move on from their past and the only way Eram knows to do that is through violence. Kris lost the headband, they never actually got the chance to cope with their insecurities and move on them from. Eram doesn't just want to die, they want Kris to straight up MURDER them.
Through killing Eram (or refusing to) it makes Kris stronger. I suspect the two options would be paralleling both Noelle (in which normal Noelle gets over her fear of mice because they're not so scary anymore VS weird route Noelle who gets over her fear of mice because she knows she can kill mice) and Flowey (His kill or be killed mentality). Through killing Eram Kris becomes stronger but doesn't fully accept their past and just moves past it. They're stronger now. Sparing Eram could see Kris accepting their trauma and past as apart of themselves. Something that can't be ignored and only through reconciling with it and moving forward do they get actual internal resolution.
