Um...whether it's used predicatively or attributively, it's a participle either way. My point was "escaped prisoner" but ?"escaping prisoner"? Given that -ee is originally derived from a past participial form, this may be significant. Again, consider:
*devoting person -- devoted person -- devotee, *devoter ?retiring person -- retired person -- retiree, *retirer ?escaping person -- escaped person -- escapee, ?escaper standing person -- *standed person -- standee, ?stander
Looking at that, now I'm wondering to what expect aspect is involved. There's a certain habitual aspect to -er that isn't necessarily present in -ee. For instance, a runner isn't someone who ran once, but someone who runs regularly (generally as a sport). "Escaper" would seem to imply someone who escapes regularly, not someone who has attempted it once. This would help explain the participle distribution, since the present participle is used for ongoing events whereas the past participle indicates completed events (and the states arising from them).
no subject
*devoting person -- devoted person -- devotee, *devoter
?retiring person -- retired person -- retiree, *retirer
?escaping person -- escaped person -- escapee, ?escaper
standing person -- *standed person -- standee, ?stander
Looking at that, now I'm wondering to what expect aspect is involved. There's a certain habitual aspect to -er that isn't necessarily present in -ee. For instance, a runner isn't someone who ran once, but someone who runs regularly (generally as a sport). "Escaper" would seem to imply someone who escapes regularly, not someone who has attempted it once. This would help explain the participle distribution, since the present participle is used for ongoing events whereas the past participle indicates completed events (and the states arising from them).