There's a real charge between Aries and Scorpio - both are driven, willful, and unafraid of a fight - but the 150-degree quincunx keeps it from ever being an easy fit. They share a certain Mars-flavoured intensity, yet they run it completely differently. Aries is Fire, fast and out in the open; Scorpio is Water, deep and hidden, playing a much longer game.
The tempo gap
The tempo gap is the crux. One discharges anger in a flash and forgets it by dinner; the other holds everything in - grudges included - and reveals only what it chooses, playing a strategist's long game. Aries wears its whole hand on its face; Scorpio keeps its cards down and watches. That difference in tempo and transparency breeds suspicion: Aries finds Scorpio's secrecy exhausting, Scorpio finds Aries's bluntness naive.
Aries and Scorpio in love and friendship
Romantically the attraction can be powerful and combustible, two strong wills circling each other, but it's prone to power struggles - Aries pushing for openness and immediacy, Scorpio controlling through depth and withholding. It survives only on hard-won trust, which Scorpio grants slowly and Aries has to earn by not trampling. As friends, once that trust exists, the loyalty runs fierce on both sides; each respects the other's flat refusal to back down.
Beyond the sun signs
As ever, treat this as one thread, not the whole weave. A quincunx between two suns is barely a thirteenth of what actually determines chemistry - how the two Mars energies collide, and what the cross-aspects add, carry most of the weight. Aries and Scorpio with kinder contacts elsewhere can bond intensely; the sun angle just guarantees they'll keep having to adjust to each other.