New Answer:
Could you be
PRISM?
Pry for the prefix, all you need is my eye; or was it yours? I don’t know why.
PRI. "Pry" for the prefix.
Into the infix, stare for a while; it’ll slip past you, while it sits back and smiles.
IS. There is an album called Prism by Katy Perry, with a song called International Smile.
I. You stare with your eyes. The actions "slip, sits, smiles" all contain i.
S. You can stare at it. The actions "slip, sits, smiles" all begin with s. Also, "slip past you" $\to$ "slip past u" $\to$ "slip past u" which are letters of the alphabet in their order starting from s.
Now for the suffix, in my music its blaring; I think it’s time for another red herring.
M for music? This is the only part I cannot explain, but music is definitely related to the answer.
Keen on music? This band knows the way; with Floyd you’re not wrong, quite an album to play.
There is an album by Pink Floyd, also called Prism.
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Title:
That is colourful!
Also,
The acrostics spell PINK as it refers to Pink Floyd.
Original Answer:
Could you be
EVIL?
Pry for the prefix, all you need is my eye; or was it yours? I don’t know why.
E. There is something known as the evil eye which would be all you need, as this answer is very much related. It is said that people with "looks that can kill" have an evil eye, and you might not know why.
Into the infix, stare for a while; it’ll slip past you, while it sits back and smiles.
V. It comes after U (you) and looks like it is smiling (if I add eyes, it looks like it is smiling: $\stackrel{\bullet\bullet}{\rm V}$) Another word for a "slip" could be envelope, and staring relates to eyes $\to$ evil eyes.
Now for the suffix, in my music its blaring; I think it’s time for a red herring.
IL. In music, there are pieces. In the OP's "pieces" (riddles), there is one main thing that is red: the Vermillion. The part that is blaring in the word (that occurs the most) is "il" (Vermillion). Also, villains can be pretty evil sometimes, and that word contains "il".
Keen on music? This band knows the way; with Floyd you’re not wrong, quite an album to play.
This refers to Pink Floyd who sang a song called Money, which is commonly referred to as "the root of all evil". In fact, that is one of the actual lyrics to the song (namely, "Money, so they say, is the root of all evil today.")!
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Title:
I cannot really explain the title, but the name Lucifer is hidden in it (A C${}$o${}$l${}$o${}$rfu${}$l R${}$i${}$l${}$e${}$y $\to$ Clrfuie $\to$ luCifer).
Also,
The acrostics spell PINK as it refers to Pink Floyd and the "colour of evil". I mean, guess who's the bad guy in the following picture.
Clearly, it is the guy with the red (pinkish) lightsaber.