hence my confusion a few pages earlier about her long term arc.
her joining the faceless men doesn't serve purpose to her killing people off her list. She is being told to forget who she was and all the hate that associated with it.
I think the thing there is that she's a kid and is struggling with that choice.She went to Braavos not knowing what she was gojng to find there- now shes been offered the power to become something that would be capable of erasing everyone on her list, but to become that she'll have to renounce herself and her personal ambitions. And then add into that fact that shes still a Stark, with a Direwolf that she's bonded to out there somewhere... shes a joker in the pack right now.
also, is it ever explained wtf jacqen was doing there in the cart the night it caught fire?
Yes- although the official explanation isa bit suss. He, Rorge and Biter were being transported to the wall to take the black with the other criminal recruits- they were in the cart because they were apparently particularly dangerous criminals that had been kept locked in the black cells of the Red Keep, it's most secure dungeon. now thats plausible for Rorge and Biter- we know they were particularly nasty, dangerous scumbags who'd probably been caught doing hideous things. But its doubtful a Faceless Man would be held there, if one could be captured at all, you'd think they'd be immediately put to death, or at least tortured to death in an attempt to discover their target. So you'd have to suspect that he somehow meant to be there- and that the Faceless men are in on some grand scheme- which at a wild guess would potentially mean Varys was involved somewhere, as he often seems to be at that level.