suis

Etymology 1
From, from , from. The expected Old French reflex of would be. The form goes back to  or earlier *suī, which were probably influenced by the perfect tense  (“I was”, modern ). Compare the reverse development in 🇨🇬, from, influenced by the present form. Final -s was added in later Old French to the first-person singular forms by analogy with the second person; it was standardised in Modern French in most cases except after unstressed -e and in the ending of the future and past historic.