was that ever explained? Avenger is basically a Shirou recolor,
maybe he just took on Shirou's form? like in the daytime.
or there could be some kind of family tie since we never saw Shirou's real parents.
or Nasu was lazy, like how he recolored Shiki's shirt and made it Shirou's
Community Crucis member: Angra Mainyu
Beasts Lair member: Angra Maniyu
Melty Bread member: Kyokushi