Two entries with the name Alaris.
Alaris
A knight in the service of King Mark of Cornwall.
He was killed in a chance encounter with Sagremor (Sagramore) in the forest of Morois (Morrois).
Source
Prose Tristan | 1230-1240
Alaris
A knight who cuckolded Sir Claristant by riding off with his amie. Claristant caught up with them and engaged Alaris in combat. Alaris was assisted by Claristant’s treacherous maiden. Claristant would have been killed, but Kay and Gaswain intervened and saved him.
Source
Prose Tristan | 1230-1240