I have been lurking on this thread for awhile. I think many valid points and speculations have been made and I truly wish we had more information to go off of so that our thoughts were more than just speculation...
As many others have stated, I don't think this night-as dramatic and ultimately tragic as it was--is that out of the ordinary for hard-partying college students and I don't think that the majority of the information we have about that night is shocking being that I (despite obviously not knowing anyone in this case personally or having attended or ever even been to IU/Bloomington) have just recently finished college myself, not very much older than Lauren or the PsOI and, though I mostly stuck to just drinking, have also been exposed to/semi-involved in the drug culture prevalent at many college campuses/among many in this age group.
I think it is most likely that this is either a flat-out OD or accidental death at least partially caused by substance use (heart condition exacerbated by strenuous activity (sex, a fight, stress, mixture of substances), fall/hit head, etc) and cover-up involving JR and one other person. If drug use was widespread among one or both of these groups of friends (JR/CR/MB/DR/HT and JW's friends), that could account for a lot of the ambiguity we've been seeing and inconsistencies or seemingly odd statements made in the PsOI and friends' reports.
It is interesting to analyze all the various elements of the night and ask why did all these things happen/they make little sense (for example, why did they go to JR's apt before Kilroy's to 'watch the game' when the game was over at that time, why was Lauren the only girl around/why didn't any of her friends or even JW go with her, why did she get into Kilroys despite being underage, why did she lose/forget personal items all along the way, why did she and CR go back to Smallwood, why did CR get into a fight, why did they decide to leave Smallwood after the fight instead of visiting Lauren's apt, etc., etc.) but it could very well be that all of those things that we are asking ourselves 'why' about were just part of a 'normal' night of partying and do not, in themselves, have much bearing on Lauren's eventual disappearance.
What would have bearing would be the things we do not know-did she use drugs, if so, which ones, how much did she take on the night in question and how much had she used them before, how much did she drink on this particular night and was that a normal amount for her, were she and CR more than friends, who did she exchange texts/calls with that night and what were the nature of those interactions, who did she interact with at the bar, did JW know about/did he actually ask his friends to engage in the altercation w/ CR (it is possible that HT or another Smallwood resident could have told JW that Lauren was going over to JR's apt or that she was at the bar w/ CR). We have way too many unknowns. I think the most helpful information would be to know about the possibility of drugs involved-not just on the night of Lauren's disappearance but with her/amongst her groups of friends in general. I don't know why but I suspect JR was somehow involved in distributing drugs to this group of friends and that he had connections to people higher-up in the drug trade. That would explain why Lauren went to his apt before going to Kilroy's, why HT would try to cover up the drug use going on at JR's apt by saying that Lauren and DR had gone there to watch the game (which was already over by that time), why she was allegedly so messed up while at the bar (according to the supposed witness who overheard her talking about taking xanax and coke), why she may have left her personal items all over town, why she would have made weird decisions like walking CR back to his apt. after the fight. Drug use/excessive alcohol use would also explain CR's memory loss for those who do not believe the fight alone caused his memory loss. Drug use would explain why LS asked MB if he wanted to party and he demurred. Drug use would explain why LS went to JR's apt from MB/CR's apt. if that in fact happened.
Connections to powerful people in the drug trade would also explain the discreet disposal of LS's body and the lack of evidence--I think there are some people involved in drugs who would be very skilled at getting rid of a body/evidence in a case where their college dealer's friend dies of an OD, especially if selling drugs to IU students is a huge part of their business, they obviously want to do a really thorough job of covering up any accident involving a student taking their drugs This is why I think JR called someone higher up in the drug trade to help him after LS ODed or had some other drug-related accident.
I know much of this has been stated before and it is very rambling but I have been reading through these threads all day, reading up on news reports about this case all day and kind of got carried away sharing my two cents
I really hope they find some answers soon--I feel just horrible for LS, her parents and everyone involved. So heartbreaking.