He had a juicier role in the 2-part finale Dark Water and Death in Heaven where he met the recently-deceased Danny Splink and arranged for Danny to be alone with a small boy. Needless to say, Danny was truly in heaven.
The Upshot Edit
Seb added nothing to the stories he appeared in nor the overall story arc of Season 8, sadly, and didn’t even get a scene with 12 himself! His addition to the cast reeks of the character having been shoehorned in at the last second after he phoned up his old friend P-Cap D. and begged for a part, thus stealing (and doing nothing with) scenes that rightfully should have gone to Missy to develop her better.