SPM = Ninja: very dangerous, dark opponent. Known far and wide as very intelligent analytical type.
Lalaith = French maid: french associated with freedom? maid suggests freedom in service to something else? Known equally as intelligent analytical type.
special plant = ? - - the mystery element. Healing properties? Magical properties as likely. At any rate, the artifact great value.
Eomer = shirriff - the law representative, but a rather swashbuckling type; if in Texas, however, that would fit.
Motorcycle =
Roa's self image: quick, agile, little room for passengers, able to squeeze through tight traffic.
Nilpaurion on motorcycle armed with machine guns = the protagonist's equal, more threatening and dangerous than SPM or Lalaith.
Texas = land where law is in the eye of the beholder.
Were SPM or Lal attacking you? Were you trying to get at the plant?
So far inconclusive. Need questions answered first.