Lulu

Lulu was a hollyphant the savage seven discovered weeping over the corpses of adventurers in Avernus, near the city of Elturel. She explained that she came there with the adventurers to free Elturel and return it to the material plane. She also revealed that she was once a companion of the Angel Zariel, who attacked Avernus with a group of Paladins known as the hellriders. The hellriders, however, betrayed her and left her and lulu stranded in Avernus. Before being captured, Zariel asked lulu to hide her sword:

“I was with the angel Zariel when she assembled her army of Hellriders to attack Avernus. Through the gate we went, tearing through devils like a song through air. Victory was within our grasp until some of the Hellriders betrayed us. They retreated through the gate and sealed it behind them."
“Before she was captured, Zariel told me to hide her sword so that it wouldn’t fall into evil hands. Someone helped me hide the sword, but I don’t remember who. We found a place to hide it, but I don’t remember where. I escaped Avernus, but I don’t remember how. Most of my memory is gone, and I don’t remember why.”

The Savage Seven agreed to help her in her task, if only to reach Zariel (now the archduchess of avernus, and the devil behind their contract). Lulu led them to Fort Knucklebone, where they encountered Mad Maggie and her gang.
Lulu continued to follow them all the way to the sword of Zariel. When they failed to redeem her, she fought alongside them against her former friend and master. With Zariel dead, she decided to serve Kathra and promised to come to her should she ever have need of a companion.