Three Kingdoms: I Ran for My Life with My Pants Down from the Start

It's the same old transmigration story, except from the start, he's serving under Yuan Shu... Is this what they call a disastrously bad start? So he'd better get out of there, fast... A nobody in a fight, a strategist, a man with three surnames... Hmm, no, a wise bird chooses the right tree to nest in. This story tries to follow the official histories. If you disagree, feel free to join the discussion in the comments...