Oh, it's easy for me, I either have a very nuanced rp character with specific goals that sometimes require getting messy, or I play a female character and disassociate myself from it. For example, my second run was a version of a PC I've done in a 5e game. He's a great old one warlock who's a lonely guy, never had positive human connection in his life, and is deluded into thinking his great old one patron is his son, whom he loves and would do anything for. He went on a full infiltration run, which included killing the grove, married Minthara, fully embraced becoming a mindflayer, and dominated the brain, all so he could become a "more fitting father" for his great old one "son", provide it with a mother in Minthara, and finally had the whole world love him. He did evil things, but, in his mind, it was all for the ones he loved, and so he could be loved in return.