Here are some character concepts based on Sivir's lore :)
Mhyra is already depicted in sivir's lore, she was a sivir childhood friend before betraying her
Iha is already depicted in sivir's lore, she was the chief of her mercenary group. I tried to develop her visual once sivir betrayed and abandoned her alone in the desert.
Hondo is a trustworthy mercenary friend of sivir. He became her mentor and taugh her everything she needed to know when she first joined them
Haru is a young orphan. Sivir decided to save him and take him under her wing, when she saw him trapped in a ruin.
Zeth is another member of sivir mercenary group. Sly and cunning, nobody really trust him... but his great agility skills and ability to foil traps in the ruins make him a formidable asset