Games Of Thrones Season 7: What 'Beyond The Wall' Really Means
4. Jon Lives, Benjen Is No More

Almost mirroring Jaime when he tried to kill Dany himself at the end of the Loot Train Attack, Jon Snow almost got himself killed again by fighting off the wights to allow Dany and the others to escape. For his troubles he ended up dragged down into the icy depths (same as Jaime, again, then) to his apparent death, only no that couldn't happen obviously because he's Jon f*cking Snow and he's still needed.
So, he dragged himself back out of the lake (somehow) and seemingly decided to walk back to Eastwatch, managing to get no further than a couple of hundred yards before the wights noticed and bore down on him again. Luckily, Uncle Benjen turned up as we knew he was going to, swinging his bad-ass fiery chain weapon and giving Jon his horse to escape.
For some reason, Benjen then decided he "didn't have time" to jump on the horse too (ludicrous) and sacrificed himself to allow Jon to leave after a very brief reunion with the boy who idolised him. It would have been quite touching if it wasn't over so quickly, but it means the living characters have lost a very valuable ally.