Though you can't openly ally yourself to anybody, I think it is foolish to completely deny the humanity of your champions. While I would never have an ale with the man, Kassadin knows that our best interests are mutual, that I seek to learn of those from the Void and to limit their numbers in this realm. As a result, he is more willing to fight for me, he knows my intentions are good.
Now... none but the equally insane should try to form a bond with, say, Dr. Mundo, but to state that we should all stay as far away as possible from all champions is a bit elitist. We have to remember that these are legends, and we know what they are capable of... but to truly know your champions strength, and to fully harness their power, you must know your champion. Kassadin is more than a sword-carrying maniac. We are not legends in the same way that the champions we utilize are, but no company can behave when its employees are hostile and regarded like animals.
This, of course, does not mean form the same sort of link that Bob Nashahago has formed. I see nothing but misery in his future, and Nidalee knows what will become of somebody creating those sort of relationships. Nidalee's relationship with the Summoner (and in Nashahago's case I use the title summoner lightly) is likely no more than another one of her traps. Only time will tell where she leads her bait.