I took RPing to a whole new level with my Breton spellsword, Dandre. He started out as a kind, humble, middle class mage who would do anything to help the suffering citizens of Skyrim. After getting injured while defending the town of Dragon Bridge from a pack of werewolves his mind began to warp into a more darker side as the disease of lycanthopy began to infect him. He soon turned unwillingly into his beast form, unable to control himself. He rampaged around from Solitude to Whiterun killing and eating anything in his path. When he turned back to a Breton he remembered what he had done and was horrified by it. When the priestesses at the Temple in Whiterun couldn't help him he flew into a rage, desecrating the temple, running out and killing a priest. He turned himself in and contemplated what has happen while he spent the week in jail. His beastial hunger soon catches up with him again and he hunts and kills again. As the days go by his mind grows darker until he only cares about one thing, himself. He becomes disconnected from the needs of others and soon joins the DB where he finds others that accept him for what he is, although the only goal he has is to feed on easy prey and to earn gold doing it. But, he develops an attachment to Marcurio during his first visit to Riften, he doesn't see prey when he looks at him, but a mate. He begins to pursue the mage, spending time with him whenever he visits Riften, giving him Dwarven related gifts, and sometimes even takes detours to Riften just to see him or spend the night there. Dandre wouldn't dare reveal the truth about his occupation or his werewolf half.
After Dandre made sure the DB is taken care of with a new sanctuary, he decides to just leave them in pursuit of something greater, love. He feels calmer around Marc, and it's as if he can control his animalistic mind. He still feels the need to hunt, but he can control it so much now that sneaking a bit of raw, bloody meat works just as well as eating a carcass. Dandre feels the need to act like his old self around Marc, the selfless, good natured man, from clearing out a fort of necromancers to giving his amethysts away so that two Argonians can get married. Of course, he forces himself to do it, mostly at Marc's suggestions to do so. Dandre is happy to please Marc and impress him, so he basically does whatever Marc suggests. (A lot of RPing goes into it, we all know Marc wouldn't suggest some of those things.)
Dandre still slips into his dark mentality from time to time, responding rudely to others questions, threatening people when he's agitated.
I RP with Marc too, during the Unending Season quest he wouldn't set foot in the Palace of the Kings because he believed Ulfric was the cause of the Emperor's death, so he waited in the inn. Dandre and Marc had to go to Kyensgrove to spend the night at that inn because Marc wouldn't sleep in Windhelm. I like to think that Marc wouldn't be involved in politics yet he's still a citizen of the Empire and therefor outraged that Ulfric would do such a thing.
I plan to do so many more things, including something even more dramatic in the Dawnguard questline.