Ron Stoppable

The Mystical Monkey Power has made Ron a lust magnet, and has unfortunately made his cum almost a guarantee of impregnation – as a number of girls have learned. He finally caught on to this fact and tries to pull out, or cum somewhere other than her pussy. Condoms don't stop him. Her being on the pill probably won't stop him – the MMP often causes her to ovulate.

Oddly enough Kim is one of the few girls he hasn't fucked. Kim's cousin, Jocelyn, had a crush on Ron and snuck into his bedroom and started riding him, cowgirl style. Kim came in and discovered Ron fucking her cousin. Ron swore he didn't know it was Jocelyn, he thought it was Kim. Kim has small tits, but Jocelyn is flat as a board and Kim is certain he must have known. Insulted (and suspecting Ron lied) Kim hasn't screwed him – although he continues to be a close friend. (Jocelyn was not seen or mentioned again. In one fan thread a writer suggested Ron had knocked her up in their encounter, and just like Jamie Lynn Spears was dumped from Zoey 101 when it was discovered she was pregnant the same was done to Jocelyn)

Much fanfiction converts the MMP into a really big cock, and Ron stars in frequent harem fics where he screws everyone. He has a soft place in his heart, and a hard dick between his legs for Bonnie, and she occasionally throws herself at him. And Shego is a frequent sex partner as well. He's knocked up Shego many, many times in fanction & Rule 34 art – even beyond the harem stories where he has knocked up every female in Middleton except his baby sister. Kim's mom frequently feels the old monkey power as well and he may have lost his virginity to Ann.

Ron will hit on any girl, and even if nine out of ten turn him down he's still making it with 10% of the girls he encounters.