First off, I do not know where the best place to put this topic would be, so I apologize in advance to any moderators who have to move the topic for me. I appreciate what you do for the site and typically try not to make your job harder than it typically is.
Second, my question is a bit of a multifaceted one, not covering just one topic, but kind of branching out in multiple questions, and it sprang to mind from several different instances rather than just one moment. I'll be explaining a bit of how these questions came to mind first, then I'll ask the actual questions.
So, the other day, I was helping a friend who had a copy of RM 2k3, they'd recently gotten it and wanted help from me, the local RM guru (read, messes around with Ace and MV) to help with a game he was planning on making for commercialization. One of the tracks in 2k3's RTP, I noted, sounds very similar to Final Fantasy's Prelude theme, which I thought was neat . (I believe it was 'mystery2', but don't quote me on that.) They'd set that particular one as the main title theme, because their game is an homage to Final Fantasy. Earlier today, I was messing around with LMMS, learning the program and trying to learn how to make music. My friend's usage of 'mystery2' as the title theme inspired me to replicate the Prelude theme from Final Fantasy to get a feel for composing by ear. I made a fairly good rendition. This caused me to question what would happen if I were to use it in a commercial game, then fridge logic set in where I realized the implications of such reaching back to my friend.
As such, here are my questions: First, can my friend actually use 'mystery2' commercially without repercussion? Second, at which point does imitation (My attempt at making something similar, but not the same) cause the primary holder of a intellectual property (In this case, Square Enix with the Prelude theme) to tell me not to use something I made in, maybe, five minutes by ear because it's too similar? Where is the line drawn? I'm probably not asking all of the right questions, I either can't find the right phrasing, or I had it, but forgot.
(And for those who would ask, the rendition I made is just the classic up and down sound without any accompaniment, just a fade-in/fade-out gimmick with the instrumentation. I'm not particularly dead set on using it commercially, and I already know that using resources ripped directly from commercially released games is a big no-no, I actually explained that, in detail, to my friend when they wanted Samus as the main character. My main concern is in where similarity gets you into trouble. And to make sure my friend won't get in trouble for using RTP stuff because, again, the mystery2 track sounds a lot like FF's prelude.)