Toonbriel is the original name of Gabriel. He is the true Gabriel before Alternate Gabriel took his place. Toonbriel is the messenger of God and an Archangel. He was once depicted as a simple cartoon character from The Beginner’s Bible, but in truth, he is the original Gabriel.
(Headcanon: Alternate Gabriel is Lucifer, while Toonbriel is the true Gabriel. Yes, they are brothers—now standing against each other.)
I don't know what happened to Gabriel but I'd say he's fine in my headcanon.