Game of Thrones rarely has unitasker characters. Like Alton Brown, the show believes characters, with few exceptions, should be multitaskers. For instance, Cersei isn't just a bad guy, she's also a complex emotional character who drives others to misbehave. Jon isn't just a good guy, he's also an inept leader who causes coups to happen in his general vicinity. But Beric Dondarrion is different. He's been a unitasker from the beginning, and now he's been used up. Beric died on Game of Thrones, Season 8, episode 3, to the surprise of just about no one. Warning: Spoilers for Game of Thrones Season 8, episode 3 follow.
Fans have wondered since the beginning why Beric stayed alive. He actually isn't alive in the books. In the novel, he passes his ability to continue living to Lady Stoneheart, a character cut entirely from the show. Instead, Beric kept popping up, not dead yet, though fans at home were not really sure what the purpose of keeping him alive was.
Some assumed it would be to kill the Night King. Others thought it might be to help Jon in that quest. It turned out all those theories were wrong. Instead, Beric's ultimate mission was to be in the right place at the right time to save Arya.
On a weird level, this actually makes sense. Beric is, after all, a replacement for Lady Stoneheart. Lady Stoneheart is the dead version of Arya's mother Catelyn Stark. It would make tons of sense for Lady Stoneheart's ultimate mission to be to keep her daughters alive, and to die in the final novel as a way to save Arya so she could live on and perhaps take down Cersei and other names on her list.
But since there isn't a Lady Stoneheart, Beric has taken her place, and that means Beric's ultimate fate on the show is to fulfill the same purpose. Therefore, even though on some cosmic level it makes zero sense for Beric to die to save the life of a child (Arya) he barely knows and only traveled with for a small time back in Season 3, that's his fate.
Fans might complain about this being Beric's ultimate fate, hoping for him to have been meant for something greater. But the Lord of Light works in mysterious ways. Consider, for instance, that Melisandre followed Stannis around for years, even though he wasn't anything to anyone. Consider that she burned Shireen to death, and for what? So Stannis could die in a pointless and foolish charge at the Boltons. You cannot tell anyone that makes sense. It's all just the weird way R'hllor works.
So perhaps Beric dying so Arya could live will have a point down the line. After all, Shireen's death led Melisandre to Jon Snow, and ultimately to Dany and this fight. The paths may be strange and look nonsensical to an outside viewer, but those who follow the Lord of the Light trust him to make it all work in the end.
RIP Beric, let him rest well.