How Aries and Leo work together
Aries and Leo are the pairing sun-sign columns love to recommend: two fire signs, both direct, both happiest when something is happening. Mars rules Aries and the Sun rules Leo, and in Vedic astrology those two planets are friends in both directions, which scores the full five points of Graha Maitri.
The complication is Bhakoot. Leo is the fifth sign from Aries, and the 5 and 9 relation is one of the three that score nothing. The texts do not object to the chemistry. The fifth and ninth houses govern children and lineage, and the objection is to that axis. Because Mars and the Sun are friends, the recognised cancellation applies, so the dosha is answered even though the seven points still show as lost. Five of twelve on paper; in practice, one of the stronger pairings in the zodiac.
What goes wrong is precedence. Aries wants to start things and Leo wants to be seen leading them, and neither enjoys following. Couples in this pairing tend to do best when each owns a domain outright rather than sharing one. The Vedic caution about progeny is worth taking seriously in one narrow sense: with two dominant temperaments, decisions about children are where the unresolved contest over who leads usually surfaces.