Sumbra is LuxrayTale's Muffet, he's a Glitched Umbreon who started selling pastries to help defenseless Eevees find loving homes. When you see him in Hotland, he has 2 Eevees who need homes, the one on the left is named "Sumbra Jr." & is 100 Gold, while the one on the right is "Sumbress", who is 500 Gold. By helping one of them, he'll praise you in helping them have what they didn't at first, a loving home. If neither are helped, a battle will ensue & near the end, he'll get a telegraph from the Ruins saying that you did sign his petition to help all Eevees. In the No Mercy route, however, Sumbra will notice the two Eevees he's wanting have a loving home, scared of the player, he'll say the price for them is 1,000 Gold for Sumbra Jr & 2,000 Gold for Sumbress. Since he's raising the price on the player's no mercy run.
Sumbra will even have a Side Quest after completing the True Lab's Events, by returning to the room he fought the player in, Sumbra will ask the player to see if they can find Sumbra Jr/ Sumbress (Depending on who the player took a liking to & saved), a loving home. The player can return to the ruins where Ailey is. There, Ailey will have Chrome over. During Sumbra's Side Quest, the player can ask Ailey to adopt one the Eevee that doesn't have a loving home. She'll go see Sumbra to get the poor Eevee.
If the player helps both Eevee giving them a home with the player, Sumbra will ask the Player to help him find a home for himself. The player may offer to be his new owner in return for letting the player save both Sumbra Jr & Sumbress. Sumbra Jr & Sumbress can also be strong allies in battle. During the fight with Grandmaster DoomFlame, they can help get in Extra damage with Helping Hand. During the Fight with Omega LuxrayBlast, the Eevee(s) will add in Extra Damage to the player's attacks. In the fight with LuxrayBlast Koritsu (True Pacifist), the Eevees are supporters of the player who can provide extra healing items like pies, candy, leftovers, etc, that will be great to heal with when LuxrayBlast does loads of damage.