Mass Effect: Stardust
Major Galactic Organizations
Almost nothing is certain, and these groups all have different motivations. It is best to assume they help the PCs (if they don’t attack them outright) out of a desire to further their own interests (even if PCs are members of the organization they come to for help), but in the case of some of the criminal organizations it is always possible that they don’t have immediately hostile intent. Practicality makes money, after all. Just as the PC’s party’s alignment and reputation is up to them, so are the reactions NPC groups might have to their actions.
A smart question to approach these groups with, if the PCs want their help, is “what is their motivation, and how do I help them achieve it, as well as my own?” However, if their motivation is normally “death to all sentient organic life”, then the PCs should be operating under the assumption that there is no possible peaceful interaction available with such groups. Further, keep in mind that at this point in time, some of these groups have an already-established reputation in Citadel Space, while some have none at all.
Some of the groups also have conflicting alignments and political leanings, and one can assume that if one such group likes the PCs enough, an opposing group will dislike them (for example, a positive relationship with the STG would hinder attempts to build a rapport with Cerberus). Likewise, some groups are allied with one another more closely than with others, and a positive relationship with one group may have a trickle-down effect with their ally, benefiting the PCs by reputation.