Basically Pete Wentz, Christopher Gutierrez, Joe Trohman, and Patrick Stump were all in this band together called Arma Angelus. The member thing is messy so im not sure who was officially in it from the beginning but whatever they all jammed together as Arma Angelus at one point.

~2006 from Chris' livejournal

"an open letter to pete wentz.

it takes a lot to make me mad.
it takes even more to infuriate me. so, after all this time i finally learned the truth. that it was you telling my ex girlfriend lies and secrets. despite even giving you the pass card after i caught you trying to talk dirty to her online, this is how you repay me? no wonder why you couldnt look me in the eye on the bus last summer and no wonder why you avoided me every chance you got.
you hug me and tell me you love me then you tell lies to my girlfriend behind my back to lure her away from me? you tell her i cheat on her and then you tell me to come stay on the bus?
you are a spineless fucking sham. i regret every second i spent defending you and your selfish ways.
dont forget, i know you. not that shitty glammed up poser image you present to the masses to consume. the dude i knew never would have worn a fucking dinosaur shirt or sold out one of his friends. the dude i knew had heart and fucking loyalty. well lil buddy, you are fucking done. you want to sell me out to the most important person in my life and then have the audacity to make ME think I did something wrong to not deserve your friendship? you fucking arrogant bastard.
since we’re discussing sellouts lets discuss how when kids give you presents you laugh at them and throw it straight in the trash. oh yeah, ive seen it many times. lets talk about how you talk shit about the fat girls that are your fans and mock their letters. you are fucking undeserving of every ounce of attention you’ve ever gotten. from every one of your calculated business moves to your “spontaneous” jumps in the crowd parts to your well rehearsed cliche lines you’ve been spouting for 400 shows in a row. you’re boring, contrived and old. “oooh, no one loves me, its sooo hard being on magazine covers and tv shows. someone save me from me.” what are you, fucking 12? go light your little candles ask yourself why no one will ever truly love you. its amazing no one has caught on to your little fucking show. you’re nothing more than a shitty opportunist business man with even shittier fashion sense. so pack up and move to whatever million dollar house you’ve picked out in california paid for by your lies and hypocrisy and deceit and selfishness and over medicate yourself like youve been doing for years…because guess what? no one wants you here anymore. you are not welcome. oh yeah, hows that straight edge tattoo doing? as well as the tattoo for your “crew” who now refer to you as a fraud and a con? stay gold dude, stay gold. remember this each night of the tour when you play the lie, “hey chris, you were our only friend.”
downplay it all you want by saying the song is about “friends”, but guess whos fucking name you’re saying each and every night? mine. thats right. what a bunch of fucking phonies. sing the songs you dont even believe in anymore. fucking liar. you know the friends i have and you know how we feel about loyalty.
you know who im talking about and you know they’re not happy either.
so dont get caught slipping and you better make damn sure you watch whos on your guest list because a plus one might come backstage to punch your fucking teeth out and tear the windpipe from your throat. you fucking sell out. oh, and next time you decide to write another song about me, do it right you fucking coward."

Pete responds:

"oh what a monster we’ve created. when i am called by my manager to read a post that is burning through the internet it makes me wonder. ive never responded to rumours or shittalking online, no matter who it came from- at the same time there is nothing that makes my blood boil more than reading this- being who i am, my first instinct is to blow it off- but then i consider how anytime anything is written on the internet people believe its true- no matter what, no matter the biases or subjectivity of the sources. my first instinct is to lash out- to say everything i think about you and every situation- to defend myself and attack you. as unbelievable as it is- i am an extremely insecure person- everytime i read something about myself negative or positive i react in probably the exact same way anyone would. but like i said- i am going to continue to do this my own way, what i consider to be the higher road. i understand when we get angry we often lash out- ive done it myself on many occassions. if you want to talk to me about any of this call me on my cell phone and we can do it one on one- i will not be responding to anything else- however, the attacks about our fans and the people that listen to this music and read these words is completely offbase- the fans of this band are my entire life- ive lost my girlfriend, my friends, much of my “normal” life- just to keep this relationship going- this isn’t to say that i dont make mistakes, take misteps. just because youve seen me on tv or at a show doesn’t make me anything less or more than human. you dont ever see the other side of the way we agonize over every decision we make or try our best to please everyone- because we’ve given up in bands before and we know how it feels and we dont want that to happen. everyone in the band is upset about this- remember everyone that makes up fall out boy- they all wanted me to voice that we appreciate our fans and friends that weve met more than anything- and that we realize because of where we are all the arrows are pointed at us- but we will try our best. and we do try our best. we also, have far more faith in the intelligence and dedication of the people that believe in us to think that they will be swayed easily. if you want to hear other stories of how we actually talk about our fans or think of them please ask other bands, they will testify to how we really act. we just want you to know that in four years when noone cares, we still hope you are there. im not going to freak out or whatever, but please an attack on our fans or our relationship with them as a p.r. move is uncalled for. this doesn’t need to be reposted anywhere- i am sure that fob fans know where to find it. chris if you want to talk the phone line is there. i wrote this pretty fast so i apologize for the typos and run-ons. until then, thank you to everyone who reserves judgment and has my back until the end of time. - petey"

Chris responds:

"heterolifemates.

After this Pete's yang pics get leaked, people think it was Chris who leaked them but who's to say. Also about this time is when the infamous Mikey photoshoot is done, *ALLEGEDLY* to make Pete mad. See below:

Everything above is taken from a tumblr post by @rememberwhenfob in 2013, Chris was still using tumblr at that point under @deadxstop (his url pretty much everywhere) and replied to the post saying:

funny guy. 

Interesting find on r/lostmedia: