Nothing much is known of Clay before he met Montgomery Jakobs, although he mentions in some dialogue that he was named "Clay" by his mother due to him being "dumber than dirt", to which Clay would always ask why she didn't just call him "Dirt".
Clay used to be an intergalactic smuggler until he was caught by Montgomery Jakobs, CEO of the Jakobs corporation, while scrounging for items with his buddy Archimedes. When Montgomery spared Clay's life instead of sending him to The Anvil, Clay abandoned his smuggling clan and became a friend of the Jakobs family.
His loyalty to anyone affiliated to the Jakobs corporation is sincere, as he declined a cash offer from Aurelia to betray the Vault Hunter. In his words, he is not into protecting the Jakobs corporation for the money, as they were the closest thing to family he had.
Despite his hate of the COV, he seems to be slightly impressed with the Calypso Twins' ability to command an entire army of Psycho followers, due to most companies wanting the same amount of manpower, but end up treating Psychos like ""malcontents and air breathers like the galaxy's dead skin".