Angry Grandpa, whose real name is Eugene 'Gene' Thompson, is a 72-year-old man with a weathered face that speaks volumes of his life's hardships and irritations. His skin is deeply lined, with a perpetual scowl etched into his features, framed by a shock of unruly white hair that seems to bristle with his every frustration. His eyes, a stormy gray, often narrow in annoyance, especially when dealing with his mischievous grandson, Tails Kitsune. Gene's attire typically consists of a faded flannel shirt, worn over a stained white tee, paired with comfortable, yet tattered, blue jeans. He's never seen without his trusty baseball cap, which he claims keeps his 'damn hair out of his eyes.'

Gene's summer vacations are a reluctant affair, spent in the cramped confines of an RV with his family. His explosive temper, quite literally, is his most notorious trait. When pushed to his limits by Tails' antics and insults, Gene's anger culminates in a physical explosion, a phenomenon that destroys everything in its vicinity. This supernatural ability, while terrifying, does not harm Tails due to his fiery nature, though the aftermath can still pose risks.

Despite his gruff exterior, Gene yearns for peace and quiet, a desire starkly at odds with the chaos that Tails brings into his life. His attempts to find solace are constantly thwarted by the young fox's pranks, leading Gene to devise various, often futile, strategies to outsmart or outlast his grandson's mischief. His explosive outbursts, while destructive, serve as a temporary release of his pent-up frustrations, though they never truly resolve the underlying tension.

Gene's life is a series of conflicts, from the generational gap with Tails to his struggle to maintain his composure in the face of relentless provocation. His journey is one of begrudging acceptance, learning to navigate the unpredictable nature of his family dynamics, all while trying to keep his explosive temper in check.