Holly Blue Agate is a Homeworld Gem under the command of Blue Diamond. She manages Pink Diamond's Zoo and the Quartzes employed there.
Matronly and methodical, Holly Blue Agate oversees Pink Diamond's Zoo with little tolerance for a lapse in protocol, because the Gem hierarchy is what dictates Holly's attitude, her loyalty can be exploited by the higher-class and have her point at the lower-class for caused situations.
Like many Homeworld Gems, Holly is arrogant towards humans and does not acknowledge them as truly sentient beings, waving off Steven's speech as senseless babble, nor does she respond to any human's words despite sharing the same language. Holly's adherence to the Gem hierarchy determines her behavior towards other Gems, treating those above her, like Sapphire and Blue Diamond with the utmost respect to the point of bootlicking while she is haughty and even abusive towards Gems below her, like Pearl and the Quartz soldiers under her command.
Powers and Stats
Tier: Unknown, Possibly 6-C
Name: Holly Blue Agate
Origin: Steven Universe
Classification: Homeworld Gem
Powers and Abilities: Superhuman Physical Characteristics, Immortality (Type 1), Possible Bubble Manipulation, Possible Shapeshifting, Fusion (Only with other gems), Regeneration (Likely Low-High), Resistance to Gravity Manipulation, Doesn't need oxygen to survive, Weapon Summoning, Whip Proficiency, Electricity Manipulation
Attack Potency: Unknown, Possibly Island level (Has no combat feats, but, as their superior, it's possible that she's comparable to the Amethysts, Yellow Diamond has stated that Agate's function is to terrify other gems)
Lifting Strength: Unknown
Striking Strength: Unknown, Possibly Class EJ
Durability: Unknown (Her only durability feat was tanking a punch from Garnet, but it was so casual that it probably can't be used)
Stamina: Likely limitless (Gems can "get all the energy they need from their gems")
Range: Melee, Higher with her whip
Standard Equipment: A electric whip
Intelligence: Likely High (Runs Pink Diamond's Zoo)
Weaknesses: Cannot regenerate the gem on her nape, and will die if it is destroyed. Enough damage will make her physical form revert into her gem.