If the already established hens were pecking at him, that is almost certainly dried blood. It would also explain his lethargy, as roosters can actually be "heartbroken" if they are not allowed to be the dominant alpha, as roosters are genetically wired to be.
I've personally had it happen, and learned my lesson, years ago. He actually lost all interest in eating and drinking, and I had to slowly nurse him back to health, then slowly, one at a time, re-introduce him to other chickens, starting with the most timid and quiet ones. It was quite a learning experience! So make sure this fellow is eating and drinking normally!
If you plan to add other chickens at any time, a large dog carrier or crate would be a good investment - and they can be had, at thrift shops or on craigslist, etc., for a decent price. Keep new birds in the crate for 30 days, to watch for any hidden problems or diseases. Also always care for your existing flock
first, and then any new birds - then wash up very good (and it's even a good idea to change clothes) afterwards, too. It can save a world of heartache that could happen if you put a diseased bird with your flock, or even accidentally transfer dangerous germs from the new bird to your flock, thereby losing all of them.
I've known friends that learned that lesson the hard way, too.
The best trick I've found to integrate new birds into a coop of already established birds (after the 30 day quarantine), as strange as it sounds, involves garlic powder.
Get an extra-large jar of it, sprinkle the entire coop with it, and all of your birds (under wings, on back & work it down through their feathers to their skin, etc), including the new one. Then, after dark, once everyone's gone to bed, put the new chook in on the roost next to the others (with as little light as possible, so everyone stays calm). The garlic smell covers any scent differences, so they don't immediately figure out the newly introduced chicken doesn't "belong" to the flock, and moving the new one at night allows everyone to wake up together, and it seems their little minds just assume the new bird was always there.
LOL, I know it sounds silly, but I have successfully integrated many new chickens to multiple different coops that way, with virtually zero trouble! The only time I had any problem was when a new roo thought he could take over before the old rooster was willing to step down.
That could have happened in any situation where a maturing roo was in the same coop as a much older rooster, though.
Sorry if I sound like I'm lecturing, but I like to be honest, even blunt, because that's what I would prefer others do to me. Honesty is the best policy, even if it comes off as blunt or overly-dramatic. I am only trying to do my best to offer the best advice I can.
I hope your fella has finally started to integrate himself with everyone! And, if those spots are still there, it wouldn't hurt to put some triple antibiotic ointment on them. Be sure it's not the type with pain reliever in it, though, as that can sicken or even kill a chicken. They're very sensitive to many types of pain medication, especially the "....caine" kinds, and the antibiotic ointment with pain reliever has one of the dangerous kinds!
