So, I have a Suzy theory inspired by Chapter 2:
I think she's Susie's sister.
My evidence is the analogy Susie makes to Berdly after he gives his backstory:
(source)
This is a very specific example for Susie to make without coming from her own experience. Plus, her having a sibling would fit with Susie seemingly having never had her own room before the one in Ralsei's castle.
And if Suzy has a sister, well... remember how one of the narration lines in Asriel's room at this chapter drew attention back to the sisters Catty and Catti? :)
yeah, i think it's a good theory that suzy is susie's sister! it's an easy parallel to make between suzy/susie and catti/catty.
although i did personally interpret that line as like. in the game, the protagonist has a sister who is a party member. i think Dragon Blazers 2 is probably a singleplayer game, because the game Noelle plays with her dad is Dragon Blazers III, and you would think they'd be playing multiplayer if it was possible, considering this dialogue:
but who knows, maybe 2 is a multiplayer game and 3 is singleplayer??
although i'm also under the impression that susie doesn't have a family, considering:
- she doesn't ever mention any family members, (unless you count the dialogue you showed) nor does anyone else mention any family members
- when toriel tells her to call her parents, she pretends to go up to the phone until toriel leaves (although this could also be explained by her having abusive parents)
- she might be homeless, because:
-- she says she drinks the milk that alphys leaves in the alley
-- you can't find her house anywhere in hometown
-- when you enter the room ralsei made for her, she seems genuinely in awe of the idea of having her own room, saying it multiple times
-- similarly, she looks around with an awestruck look on her face when she enters kris's house
-- heavily implied that she doesn't have food to eat (eats chalk, says she didn't eat breakfast in chapter 1)
(obviously a family can be homeless, but a teenager with no family is almost definitely going to be homeless)
(although even in that case of susie having no family, there's the possibility of suzy being susie's dead sister, which is a whole different can of worms of an idea)