Frankly, I find the love stuff between Rei and Alice to be creepy considering he is old enough to be her father.

You're not wrong on the age difference being creepy, but he's not that much older than her: Alice's actress is 17 and Ray Fujita is 28. Still a lot of nope, but we're more in young uncle/much older brother territory.

I'm not referring to the actor's real age, I mean character wise. He's supposed to be what, 40 in the show? It takes place after Makai no Hana, after all. At least it better or he has already aged really horribly.

Does it? I assumed it took place between Makai Senki and Makai no Hana since Rei and Rekka are running around being all not old and stuff.

No I'm pretty sure it doesn't take place after Makai no Hana because Rei isn't rocking that chin spinach goatee he had in the episode. And no one mentioned Kouga and Karou being missing during the show, and I'm positive Garo being gone would have been brought up at least once. Particularly during the moments Rei and Rekka had scenes together. So it has to take place after Makai Senki, definitely after Black Blood, But before the flashback episode of Makai no Hana. No where Dragon Blood takes place with the Garo Asura special could be up for debate.

But Garo's not gone if Raiga is there because he is Garo. Plus, why would they talk about Garo when this is Zero's show?

Because more than likely Raiga is still a little kid at his point and time in the Garo timeline, therefore would not be Garo yet Kouga would still be. Considering how close they became despite the rocky start Kouga did ask Rei to train his son when he turned 10. And seeing how tight knit this group became I'm sure one of them would have asked at least once "Have you heard anything about Kouga and Karou yet?"

Also in the episode where Rei started training Raiga he told Gonza he was going to go away for a while but they would be back together, implying he was going to look for Kouga and Karou as well. Since both of them are still gone when Makai no Hana started, more than likely Rei is still gone too. So at most Dragon Blood took place maybe five years or so before he started training Raiga

I'll take your word for it since I don't remember anything about Hana outside of the horror movie episode.

Zero, Black Blood and Zero, Dragon Blood takes place after the events of
Garo, Makai Senki.

Welp, I enjoyed the series. Alice's antagonistic reveal was interesting, if only so that my dislike of her was rewarded. Plus it's always a treat to see Rekka in action.

And our Kamen Rider alumni has now been 3 villains, and 2 decent supporting cast characters.