Didn't Zeno's authority, at least at first, come from being the father of Leo II, grandson of Leo I? It seems like he was able to do what Stilicho was unable to do (if his enemies were correct in accusing him). I'm just perplexed at why Zeno was successful, while Stilicho much less successful, again assuming that he wanted either the throne or to be the power behind the throne.
Additionally, a couple of thoughts:
1) From what I understand, Stilicho was much more popular with the barbarian elements in the army, and less so with the more "purely" Roman elements, and also immensely unpopular with the Roman Senate. Also, I don't know what Honorius thought of him, though at that point it probably didn't matter.
2) Assuming he lived longer, could Stilicho pull an Aspar and raise up a new emperor if Honorius dies early without an heir? While maybe it couldn't be him, surely he could find a new emperor from either the relatives of Theodosius or perhaps even among the army?
3) I've been looking for good sources on the Western Roman Empire/Late Roman Empire, what would you say are the best? Preferably that are in English, because I don't know any other language.