He appears in the Level 3 section of the Final Chaper, where he suggests where the library's key may have gone.
He was slated to appear in the old version of Level 5 in the Level 2 section, thus he will be included in the Cut Content edition of Level 5 in the Release Party Edition. This version of Level 5 is not canon to the story of T.T.F.N. 2. His name is a play on "Robin Hood".
Sparrow Trunk is very mysterious.