Fire doubled
Sharing an element removes the usual translation problem. Neither has to explain the appetite for risk, the impatience with hedging, or the preference for doing something badly now over doing it well later.
What a shared element also removes is correction. Earth would supply caution and water would supply consequence, and neither is present. Two fire signs escalate each other's confidence, and the escalation feels like agreement rather than like a warning. That is the single most useful thing to know about the combination.
Cardinal and mutable
Aries initiates and Sagittarius disperses. That is a better division than it sounds: Aries commits to the specific and Sagittarius keeps finding the next place to go, so the pairing rarely stagnates.
It is also why nothing here holds. No fixed sign is present to insist on continuity, so commitments get renegotiated whenever a better prospect appears. Both parties usually agree to the renegotiation and then feel obscurely unsettled afterwards. Written arrangements do more work here than they would for most pairings, precisely because neither party enjoys them.
Mars and Jupiter
Mars rules Aries, Jupiter rules Sagittarius. Traditional practice calls both of them hot and dry, and they behave that way here: Mars supplies force, Jupiter supplies expansion, and nothing in the pairing supplies restraint.
Saturn is the placement to check, in both charts. A well-placed Saturn is the difference between two people who make bold decisions and two people who repeatedly discover the same avoidable expense. Neither sign asks for that correction, and both benefit from it.
Where it grinds
Money and scale. Jupiter overcommits by temperament and Mars acts before pricing anything, which produces a specific and recurring category of argument about what was actually affordable.
The second grind is tact. Sagittarius says the honest thing carelessly and Aries says the blunt thing immediately. Neither is cruel, and other people frequently experience the combination as though it were. Each tends to defend the other's bluntness and to feel wounded by it privately. The pattern holds long enough that it usually surfaces during a holiday rather than at home.
Sun signs are the coarse layer
A sun-sign description covers a twelfth of everyone alive. That is a useful sorting device and a poor description of an individual, which is worth holding onto when a page like this seems to be describing someone exactly.
What refines it is the Moon, for what each needs privately, Venus for how affection is shown, and Mars for how conflict runs. Compared across two charts, those usually outweigh the Suns entirely. Two Aries and Sagittarius couples can therefore look nothing alike from the inside.
Questions people ask about this
Is a same-element pairing easier?
It removes friction, which is not the same as being easier. Fire and fire agree readily and neither supplies the caution the other is missing.
What does this pairing lack?
Restraint and continuity. No fixed or earth influence is present in the sun signs, so both have to be supplied from elsewhere in the charts.
Do Aries and Sagittarius argue much?
They argue quickly and briefly. Neither holds a grudge well, which handles the symptom and leaves the underlying disagreement about spending untouched.
Which placements matter more?
Saturn, for limits, and the Moon, Venus and Mars for daily life. Those describe two people rather than two population groups.