Patronus are the thing that protects you, like a guardian. Whether or not they reflect your animagus form is whether or not you're dependent on another person for support, protection, and caring. For example: McGonagall casts a patronus in DH, and it is a tabby cat, just like her animagus form. Umbridge casts one and it's a persian cat, I think.

So, they are not completely different, but I think that the patronus is what a person sees as defending them. McGonagall can look after herself and is quite stern and resilient, and so she does not need anyone else to protect her, so she casts a patronus of herself. Harry casts a patronus of his father, because he sees his parents as these perfect heroes who laid down their lives to protect him. Also, as he never saw the Dursleys as guardians, he sees his parents as his true family, and, having an idealized perception of family, he sees family as a form of protection and comfort.

Ron has a dog patronus, and I have always imagined him to transfigure into a dog, if he were ever to become and animagi. I think that Ron, like McGonagall, does not feel the need to be protected.

Now, Tonks, on the other hand, whilst she is an Auror and all that malarky, does feel the need to be protected and looked after, and can be emotionally unstable. That is why, when she begins to see Remus as a protector, her patronus changes to a wolf. I find it very unlikely that her animagus form would be a wolf, as it doesn't suit her personality at all.

When deciding an animagus/patronus form for a character, you need to take this into account. Are they reliant on other people? If so, the two spells will produce different animals. If not, if they are a very independent person, they may well be one and the same thing.

Of course, it is not always obvious whether a character is reliant on other people. After all, we all thought (well, the majority) thought that Snape was quite cold, emotionless, and didn't really care for anyone. Throughout the books he appears to be extremely independent and shows no signs of wanting to change that. However, when DH rolled around, we could see that underneath all that, right in the core, he was a very lonely, bitter man, who could not move on from a lost love, which therefore suggests that he, like Tonks, was a very emotionally based person, and depended, or felt the need to depend, on other people. Of course, this was far beneath the surface, and it would be OOC to have Snape suddenly being ultra dependent on people, but the idea is still there, and his true personality, however much he tried to hide it, was there inside him, and came out in his patronus.

Snape's Patronus was a doe because Lily was the one person who he cared about and, more importantly, who cared about him, and she was the doe to James' stag. Whether Lily's Animagus form would have been a doe, I don't know, but I think her Patronus would be more likely to be a stag like Harry's than a doe, because James is her protector. I imagine that if she'd cast a Patronus when she was younger, and hated James but was best friends with Severus, her Patronus may well have been something representing Snape.

Added to this, one would think that Ron, who has a huge family, and always seems to be on some level of emotional high would be very dependent on other people, and, indeed, in DH he does seem to rely heavily on his mother's cooking. However, when push comes to shove, Ron is nearly always concerned for the rest of his family. He's always looking out for his siblings, and making sure that they are all right. Contrary to popular belief, he is like Harry in that he can be quite self-sacrificing. Therefore, he sees himself as his own defender, and his patronus form is the same as his animagus form, I assume.

As for Luna, she seems very secure with her own identity, so her Patronus may well be the same as her Animagus form would be. Actually - it was revealed in Deathly Hallows that her Patronus is a hare. *does some quick research* According to Wikipedia's handy article on hares, they live solitary or in pairs, are able to fend for themselves shortly after birth, and are usually quite shy, but go into a frenzy in spring, hence the phrase "as mad as a March hare" (how appropriate for Luna). Hmm, that all seems a lot like Luna to me, so I'd say her Animagus form would probably be a hare as well.

Here's another consideration when you think of Patronus forms. Ever since book three came out, the consept of the Patronus has always reminded me of Native American totem animals, which I take into consideration any time I choose a Patronus for one of my characters. I know these are British stories, but it can still offer a lot of insight.

Here are some helpful sights:
http://www.crystalinks.com/totemanimals.html
http://www.workingwitch.com/totems/totems2.html
http://www.totemanimals.com/contents...-02/page01.htm
http://www.sayahda.com/cycle.htm
http://wolfs_moon.tripod.com/totemroles.html


And now my rant is done, that help anyone out?

I wasn't sure where to put this, so please move it if its in the wrong place.