Why would he be limited to going back to the Ice Age... the book explained that the older the corpse the more magic was in it so presumably it's easier to resurrect an older creature then a new one.
Other then that it's a cool idea though remember that Sue was still an abomination... and the Wardens will be after this guy if they find out about him.
I think you're breaking the fifth law with necromancy, whether you're raising animals, dinosaurs or insects. It's not as bad as humans sure, but it's still bringing something back from the dead.
Also, necromancy by it's very nature twists people (hence lawbreaker). The more you use necromancy, the more you see yourself as being above the petty laws that effect others; after all, you are the master of death itself!
Still, it's not impossible that someone could redeem themselves. Saving lives, restoring the balance of life and death, combating necromancers by unravelling their spells and so forth.
It takes more energy to raise something older (but said older things are more powerful and are easier to control). Harry said that getting Sue was like lifting an engine block, and that was on Hallowe'en, the day the barriers between life and death are thinnest. If Sue is an engine block, then I'd say a mammoth or saber-tooth of some kind would be like a motorcycle engine.
I am thinking of making a 'good' necromancer character. No name yet, just some simple backstory and the refresh.
My thought was that this person was a small time necromancer, messing around with life and death. He went to Chicago a few years back, and started seeing horrible things like Kemmler's Disciples torturing people and ghosts. At the end her saw a different form of necromancy. A man riding a giant dinosaur into battle against the baddies. He renounces messing with humans, and only works with animals. He studies paleontology, etc. and works on messing with prehistoric animals. His strength limits him to going back to the last Ice Age (for now).
His refresh would be...
Supernatural Sense [Death] -1 (Optional)
Channeling [Spirit] -2
Thaumaturgy ['Wild' Necromancy] -3
Lawbreaker Stunt [Fifth Law] -1
Sight -1 (Optional)
Refinement x# -1x# (Optional)
He'd have a Trouble involving Necromancy and the bad juju it is often associated with, and the High Concept is pretty obvious as well. His Lawbreaker involves past dealings, but he is reformed.
Any other suggestions?
At best--according to Luccio in Small Favor, there's a ley line running under the Field Museum that no doubt helped Harry gather enough mojo to animate Sue.
Actually, form what we learn, in the books, Harry raising Sue is where that ley line comes form. His necromantic act created the ley line.
Well, it 'hinted' when Luccio and Harry and Molly are looking at the Ley Line map. Re-read the character interplay and Harry's comments there and oyu'll see what I mean. Not outright stated but its there, between the lines
Actually, Luccio states in Small Favor that one runs directly under the Field Museum; it didn't pool there at all. Harry was able to use the energy of the Ley Line to reanimate Sue, and that was is the middle of a huge ongoing ritual (i.e. the Darkhallow) and on Halloween night; I don't think he could have done it otherwise.