One is the thunder and the other is the lightning.

And like any natural pair, Francia Raisa and Selena Gomez have gone through both good times and harder ones. But at the end of the day, their friendship isn't going anywhere. 

"I think our support for one another just means everything," Francia told E! News at the American Heart Association's Go Red for Women event on Jan. 31. "I mean, we've been friends—God, we met in 2008. And just like any sibling, we go through our ups and downs."

She added, "And one of the best, the best friendships that I know, you go a year without talking, and then when you see each other again, it's like you never went a day without talking. So, that's where it's at."

The How I Met Your Father actress also noted why she sees their relationship as more of a sisterhood.

"Yeah, I'm not close with her friends. I'm not close with my other two sisters' friends," she explained, adding of Selena, "She calls me and we catch up and we do our thing. We know each other's friends, but it's not like that."