Keith has been gone from the team for a long time. In fact, he’s been gone from the team longer than the other Paladins know.
Lousy space-time distortions…
Basically, two things happen here. In a minor subplot, Lance realizes he’s smitten with Allura. Hunk and Pidge make fun of him, so he confesses to the mice. Now, the mice can’t talk…except to Allura, and they tell her later. She seems…surprised.
But the real crux is a mother-son mission for the Blade of Marmora. Keith and his mother Krolia are tracking some quintessence from an unknown source through space. All Krolia knows is she found an otherwise destroyed ship with no markings and signs of quintessence and a trail showing the ship seemed to have come out of the quantum abyss, a weird place where time and space distort like crazy. Their ship is destroyed, and the pair hop asteroids on the edge to try to go around the thing despite the fact that can’t possibly work before they run out of food or water.
But the abyss gives off these white flashes of light that allow Keith to see his parents’ past, how Krolia came to Earth as an undercover scout to prevent the Galra from finding the Blue Lion, how she met Keith’s father and then had a baby with him, how she left to protect the Earth (and her son and husband) from possible future Galra attacks, and the two bond over it. Then, as luck would have it, Keith spots a gigantic space whale floating through the abyss like it’s nothing, and the pair realize they can hitch a ride on a thing big enough to have its own atmosphere. They even rescue a space puppy in there that grows up into a teleporting space wolfdog.
And then we get to what’s in the middle of the abyss, the source of the quintessence, and…well…it’s a rather idyllic place with at least one Altaean living there.
That was unexpected.
Also, Keith and Krolia were, from their perspective, gone for about two years as opposed to a couple weeks.
That was even more unexpected.
Keith is going to have some stories to tell the others if he ever gets back to them.