His Cold Disease
After an accident in his cryogenic lab, he can no longer survive in temperatures above freezing.
Change I would make
What happens when exposed to extreme cold? Hypothermia. A real "cold disease". Surviving extreme hypothermia can result in lost limbs, noses and ears, and permanent damage to the skin. A huge part of Freezes character is feeling like he is a monster from his condition. This is a natural way to achieve that. This change also helps with the next iconic and bizarre aspect of Freeze...
His Refrigerated Exoskeleton Suit
I get Freeze needs the suit in the comics to keep him cold, but why is it also an armored exoskeleton? Did he build it to commit crimes?
Change I would make
He lost a limb or two from the hypothermia, and his muscles atrophied. So maybe Bruce uses Wayne Technologies to help Mr. Freeze recover, giving him cutting edge prosthetics to help repair his weakened body. I wouldn't go crazy with this and make him have superhuman strength or anything, but it could enhance his overall look, and add mechanical sounds to his movement that could be really menacing in the right context.
The other part of his suit,
the refrigerated part, isn't necessary with this take on the character, but we still need Mister Freeze to look like Mister Freeze, and have a logical reason for him to look like that. Instead of his suit keeping him cold, what's far more straightforward for a villain who uses cold as a weapon, is a suit that keeps him warm. The main visual of his costume should be a cryo lab suit. Something a cryogenics scientist would absolutely have.
Freeze Gun
You can't have Mr. Freeze without a freeze ray. The main change I would want to see here is removing the gun aspect of it. Although it isn't necessarily realistic, what I think would feel more realistic, is if the device worked visually in the same manor as the machine that went awry during Freeze's accident. So instead of a gun that shoots a concentrated beam of cold, I imagine something more akin to a briefcase like device that emits a massive cloud of sub zero fog. This would really explain his need for the suit as well.
Motivation
Instead of having Freeze committing robberies to fund his research for a cure for Nora, I would have him just straight up think she's dead, and instead his targeting of Gothcorp is entirely about revenge. At least at first.
The plot would be something like:
- Freeze is a cryogenic scientist working for a small technology company, who's obsessed with perfecting cryogenic technology as fast as possible so he can put his beloved wife Nora on ice before she succumbs to her yet-to-be-cured disease. He gets the technology ready for human trials, but for Nora to be put on ice requires her to sign papers that ostensibly make her living remains the property of the company.
- Gothcorp sees the potential in Freezes work so they hire a corporate saboteur who goes to Freeze's lab and traps him, hoping to make it look like Freeze died of a lab accident. This results in Freeze's frostbite, and causes the company to go bankrupt where Gothcorp quickly buys them out, making Nora's body property of Gothcorp.
- When Freeze survives the accident he is furious, thinks he's a monster, and goes on a rampage against the Gothcorp executives, and anyone involved in the buyout.
- He learns Nora is alive, just being kept hidden from him. He feels extreme remorse for what he's done, making him more willing to consider accepting help from Bruce, who would essentially find a way Nora and the cryogenics company from Gothcorp through some Batman-centric blackmail or something (maybe tracking down the original hired gun who hurt Freeze?). Movie ends with Freeze sitting happy in prison, knowing that Nora is being cared for and that Wayne is putting a ton of money into researching a cure for her disease.
