Charlie Parker serie

[Hellohello123]

Hello,
Can anyone explain to me the fact that in the sixth book of Charlie Parker (The Unquiet), Charlie makes a description off his encounter with the collector (… as lay there, my skull blazing with pain from the force of the Collector’s blow…) when this is the first time ever that this character is mentioned? Even Angel seem to know about the Collector through the Grady house, except us the reader or at last to myself.