(SPOILERS) got a follower despite triggering no quests

[Monchey]

So i went to dukovs place for mr crowleys key, asked fantasia to steal it, went to tenpenny tower just to explore for a day, then came back for the key. I got the key, except from what i can tell, the moment i enter dukovs place, cherry becomes my follower. for no reason. i asked her to follow out of curiosity and she said ' the sooner we get there the better'. im assuming she means rivet city since she mentioned wanting to go there eariler (dont tell me whether this is true or not though). can someone help?

[Kvinden]

You must guide her to Rivet city alive as soon as possible, because you have only 3 days to do so. Don't rely on her to help you fight on the way.
Once you reach Rivet City with her... Well, you'll see

She'll follow you because you chose certain conversation with her, even if she is not the one who get the key for you. it's not a bug

[Monchey]

i meant as to why this is happening without me asking her or anything. I'm sure its a glitch as suddenly shes my follower without any explanation.

[Kvinden]

DialogueDukovsplace is a big twisted quest with a lot of conversation options and variables used also in MS14, the one with Allistair Crowley.

Cherry following is not a quest, it is the most probable outcome for Dukov's place. It is only her normal AI package, becoming the active one if the quest variable CherryGone is set in one of the above quests.
It is complicated because the same variables are used during different dialogues in 2 different quests. The variable CherryGone is set if CherryDeal or CherryOffer is true. Better say if you don't want here to accompany you, don't speak to her at all. But if you ask her about her clothes, about Dukov or call her a ♥♥♥♥♥ it is very likely she'll follow you