The entity is after Isabella because she is the only one that got away
Rabbit Knight seems to imply that the Entity is haunting Isabella and anyone close to her, simply because she is Thomas' daughter. It also implies that the Entity is angry about Isabella not having died with the rest of her family like she was (possibly) supposed to. There is no "entity", Thomas is just suffering from some form of psychosis
Frankly this WMG is inspired by the fact I don't think the game needs a supernatural monster, as I was enjoying the spooks and the mystery well enough without one. Just a deeply flawed man losing his family and friends (and getting stuck in his own videogame) because of his inner demons. Thomas displays paranoia (which leads to Arthur's death, which the Christmas Special reveals is before Louis-"You've done this before") hallucinations (the thing he sees). There's some support for this as well. Though Peter's existence implies that that there's someone else involved, Peter himself glitches the least of all the friends, the closest he comes to glitching is when Andy turns into Peter. The thing stalking him isn't a sign of a sinister "entity" but evidance that Thomas is hallucinating and part of what caused the tragedies was an untreated mental illness, Thomas lashing out at his loved ones, and an alcohol addiction. When Thomas himself is trapped in the videogame, he tries to find someone to assign the blame to, and picks the "entity" he believed to be stalking him as his new scapegoat (after his own daughter) rather then take responsibility.- This would mean Peter is being truthful at the end when Andy tries to say that Peter was the one who presumably murdered Arthur. Peter is, after all, a product of Thomas.
- Additionally, apparently the thing we see Andy blaming Peter for was the death of Arthur, which certainly wasn't a coldblooded kill at the hands of an evil being, but an enraged and very paranoid Thomas reluctantly listening to a voice in his head, then hacking him away.
- The Christmas Special also has this message:
Let me out I've trapped us all in here- Alternatively, given that there's a cutscene of the Entity pulling in Arthur through a screen, as well as the added fact that the existence of technology that would've allowed Thomas to download his deceased family's consciousness into the game is highly debateable. It's possible that the entity does in fact exist, but ultimately the story is telling us that it was Thomas's actions that caused the events, not the entity's. Given the entity's words.
You are fully aware of who's at fault here- Also alternatively, Thomas may have been speaking to a demon without realizing it.
- This would mean Peter is being truthful at the end when Andy tries to say that Peter was the one who presumably murdered Arthur. Peter is, after all, a product of Thomas.
Someone came up with this compromise to the above
Peter is a tulpa, a magical being with agency, but was born from Thomas's dark thoughts. It's focused on Thomas because of that. Thomas is angry at Arthur and Kamryn? The entity wants to kill them both. Thomas wants to make better videogames? The entity gives the most ruthless possible way. Thomas abuses Isabella after Louis's death? The entity declares Isabella is "MINE TO CONTROL". Andy's friends are possessed by Thomas' deceased family and want to get back at him.
- Related to the theory that Andy is possesed by Thomas, his friends are possesed by his family and the reason they act like jerks is that they despise Thomas for killing and trapping them in the game. So by forcing Andy to do the minigames is the family's way of dealing punishment to Thomas.
