Skelly

"Nice place you got here, boyo! Name's Skelly, how's it going, but enough with the small talk already, I'm here to do a job. So let me have it! Give me everything you got!!" Skelly is a Bloodless "employed" by the House of Hades as a training dummy. While Skelly claims to be on the House's payroll, he refuses to reveal who hired him and is similarly unwilling to discuss his past, instead preferring to play various pranks on Zagreus. Oddly, no one in the House seems to be aware of his existence besides Zagreus and Achilles.

Skelly first appears right after you purchase your first weapon.

Skelly has 900 HP. As he's already dead, he will simply reform after being "killed" in training. He seems suspiciously enthusiastic about getting beaten up.

Affinity
If gifted Nectar, Skelly will give you the Lucky Tooth.

After giving Skelly 6 Nectar in total, you will be unable to give him any other gift until you complete a favor for him.

Once completing his favor, giving him Ambrosia will earn you the Companion Rib.

Skelly's affinity gauge is maxed out at 9 hearts, requiring the gifting of 6 Nectar and 3 Ambrosia.

Favor
Skelly's favor is directly requested by him the next time he is encountered and his affinity gauge is as complete as it can be. He won't give you the quest until you've unlocked 4 non-Zagreus aspects of weapons. After you've done that, on your next run he should offer the new quest.

He will request that Zagreus kill him with the Stygian Blade, but using its Level 5 Zagreus Aspect (which costs a total of 5 Titan Blood), claiming it will set him free of his “contract.”

Once this has been done, Zagreus will be able to gift him Ambrosia the next time he encounters Skelly in the courtyard.

Completing Skelly's favor also completes the Eternal Rest prophecy.

After enough dialogues (and threats), Skelly reveals he was hired by Charon.

Challenge Statues
Skelly will add 3 statues to the courtyard which require you to complete runs at certain heat levels: 8, 16, and 32 to unlock. The 32 heat statue is the only reward for going past the maximum bounty level of 20 heat (25 in hell mode).

Quotes
"For quotes and dialogue regarding, please refer to /Quotes."