The Ben Franklin effect
Ask someone for a favor and they like you MORE. Your brain hates the contradiction.
Grounded in the research on https://en.wikipedia.org/wiki/Ben_Franklin_effect
What it is
A person who does YOU a favor ends up liking you more than someone who received a favor FROM you. Backwards, right? You'd think we like people we help and dislike people who make us do work. Nope. Named after Benjamin Franklin, who won over a rival legislator by asking to borrow a rare book from his library. The guy lent it, and afterward became a lifelong ally. Franklin's takeaway: 'He that has once done you a kindness will be more ready to do you another than he whom you yourself have obliged.'
The mechanism
It runs on cognitive dissonance (Leon Festinger, 1957). Your brain can't hold 'I did a favor for this person' and 'I don't really like them' at the same time. The actions are already done and can't be undone, so the cheaper fix is to change the attitude: 'I guess I actually like them.' You retroactively justify your own behavior. Self-perception theory (Daryl Bem) says the same thing without the discomfort: you infer your feelings by watching what you do. You helped them, so you must like them.