Celeres of Bonisagus
Celeres of House Bonisagus is a Grail seeker, or at this point, a Grail researcher who sends others to seek. He has a large library on the Grail and King Arthur and Merlin. He is caught up in the both the romanticism, including chivalry, and this colors his interactions with others. Many consider him mad, but do not deny his scholarship. He is a resident of the Normandy Tribunal and has been a member of the Covenant of Cunfin since 1199. He has one filius described in canon, Artorius. Celeres is the third oldest resident in the tribunal, and the second oldest currently present in the tribunal (per page 139 of The Lion and the Lily).
Most of the information about Celeris can be found in the section on Cunfin in The Lion and the Lily at pages 107-111, including a page sized insert describing his library at page 109. Mention and story ideas involving Celeres are at pages 117, 119, and 139.