Fire twice
The warmth is not in doubt. Two Leos are demonstrative, generous with money and effort, and unembarrassed about affection in public. Neither has to be persuaded that the relationship deserves to be treated as important.
Fire without another element also runs hot without cooling. There is no earth to make the generosity affordable, no water to notice what is actually being felt underneath the display, and no air to step back and look at the pattern. Everything gets expressed, and very little gets examined.
Fixed on both sides
This is where the pairing is decided. Fixed signs do not reverse, and two of them produce a household with no mechanism for climbing down. An apology is available in principle and almost never first.
The result is a standoff conducted at volume rather than in silence. Both parties are perfectly capable of holding a position for weeks, and the position is often about something small that has acquired the weight of a principle. Time does not dissolve it, because neither temperament allows a matter to fade.
The Sun ruling both charts
Leo is ruled by the Sun, so a Leo pairing has the same body governing both sides. That is unlike any other doubling: the Sun is the identity itself, not a function of it.
What follows is that slights land as attacks on the person rather than on the point. Where the Sun sits by house in each chart, and what aspects it receives, tells you a great deal about how much recognition each actually needs and from where. Two Leos with the Sun well supported behave nothing like two Leos with the Sun under pressure.
What neither supplies
Deference, and a tolerance for going unnoticed. Both want the household organised around something they are proud of, and neither wants to be the one arranging the background so the other can be seen.
The second absence is scepticism about the story. Leo maintains a version of the relationship it likes and is reluctant to inspect it. With two of them, the version goes unchallenged, and problems can persist for years underneath a presentation that both are invested in keeping intact.
Why the shared sun sign settles nothing
A sun sign is a tendency observed across an enormous number of people. Two individuals holding the same one may share very little in practice, and shared-sign pairings are not automatically comfortable.
The Moons decide most of it here, since they cover what each needs when their pride has been dented. Venus shows how affection is offered and Mars shows how the standoff is conducted. Those three tell you what the doubled Suns cannot.
Questions people ask about this
Do two Leos get on?
Warmth and loyalty come easily. The difficulty is that neither has a natural way of conceding, so disagreements harden rather than resolve.
Why is Sun rulership on both sides significant?
The Sun is identity rather than a function of it, so disputes are experienced as challenges to the person instead of to the argument.
What is missing from the pairing?
Any element that cools it. No earth for practicality, no water for what is underneath, no air for perspective on the pattern.
Does sharing a sign make things easier?
Not by itself. It confirms shared habits rather than balancing them, and the missing qualities stay missing.