Can you answer this riddle?

Question

Never feeling blue, Always seeing red

Though mostly i am skilled, I sometimes end up dead

Only killing enemies, Never killing friends

A soldier to the core, Live to die again

Those of you that play video games especially the Battlefield series should know this riddle. I can't seem to answer it though. :(

Answer 1

a soldier on the blue side and killin the reds, ppl cheat n kill u

Answer 2

popeye the sailor man! ding ding!

Answer 3

N   ever feeling blue,

A   lways seeing red

T   hough mostly i am skilled,

I    sometimes end up dead

O  nly killing enemies,

N  ever killing friends

A  soldier to the core,

L   ive to die again

NATIONAL!!!

Answer 4

I would say it's a red blood cell