Grant was very brave, an excellent horsemen and his focus is legendary. He was also an excellent strategist (Vicksburg proves this) but a poor tactician. He seemed to be able to envision the end result but tactically only knew one approach to getting there. Headlong into it , straight forward was his one an only tactic. He very well may have been an aspie. Although I think Grant the butcher is unfair. After the first day in the wilderness Grant returned to his tent and suffered some sort of breakdown and was wittnessed sobbing uncontrollable. This only lasted a short time and he recovered his composure quickly, but it did happen. A man who dosen't care about the suffering of his men does not have this type of reaction. Unfortunitly for what ever reason his assault tactics were always the same straight forward (with the exception of Chattanooga) and his casulties were always rather high. Never really thought about the aspie possibility before, interesting. Lastly I agree, had Grant been involved in illegal cotton trading or any other illegal practices he would have lived much better than he did. At one point he was so improverished when he ran into an old friend whom he owed $5.00 Grant insisting on settling the debt. The friend attempted to refuse to accept the money but Grant insisted. Finally his friend accepted the money not wanting to offend Grant. (lets call the old friend Peter)
Indeed - Grant repaid Pete Longstreet to whom loaned the money.
In U.S.Grant's youth, he had been brought up around his father's tannery, where many a horse was slaughtered as to harvest their hides. Grant was extremely sensitive and hated this business. He had a way with horses and they responded to him. Perhaps survival at youth to be a 'poker face' was a means to hide the internal emotions from a father who saw horses as 'just a horse' whereas, I am of the opinion --that to young U.S. Grant--they were individuals in a horse's body. The many stories of difficult horses that Grant would train for their owners, as to become extremely safe and gentle. Some are gifted in animal communication. "Horse Whisperer" comes to mind. I too have had horses that were difficult, abused from being difficult and I took them on and became an observer to their behavior--at times it was medical--such as an impacted tooth. Once removed all things became calm.
This world is made up with all kinds of folks, some don't make great businessmen, but great farmers; some men are awful as farmers but, great at music and it can go on and on, in every direction.
Just my thoughts and opinions,
M. E. Wolf

Could be Longstreet ticked off Lee and caused Pickett's Charge! Those charges were not the best decisions either general made but there it is.