What if Alaric is a vampire? Just a different kind of vampire. One without a set of rules. He can walk in the sun, and he doesn't need a piece of jewelry to do so. Vervain doesn't hurt him; it has zero effect on him. Obviously he can't be compelled be any vampire, not even the originals can compel him. He can run fast, is super strong just like a vampire. He doesn't have fangs though, because he doesn't drink blood. The ring he wears isn't to bring him back to life like the TV show says; no it tells him when a vampire is nearby. He can't die unless he kills a human on purpose.
If he does this then he loses all his special vampire effects. He doesn't have to be invited in, he has no restrictions that normal vampires have. He can compel other humans, but he can't compel vampires. His main goal is to kill vampires. When he blows into mystic falls to rid the small town of vampires, he falls in love with one. If he admits he is in love with a vampire he will go through a series of changes to advertise to the other vampires like him that he is not to be trusted. It is invisible to everyone except to other vampires like him. The thing is the vampire he has fallen for [Damon] won't be with him unless he says the words, but if Alaric says he loves him he automatically becomes a target.