Seems obvious Lucius(Mescal) is the lead.
And plot pretty straight forward if you know the original:
After Maximus' death Lucius(Mescal) is likely hidden away to protect him, yet somehow ends up a slave/gladiator to Macrinus(Washington), who is using him to bring down Rome's corrupt Emperors (Geta y Caracalla) who are similarly using Marcus Acacius(Pascal) as their tool in the Arena.
Lucilla is probably torn between them, as one(Pascal) was loyal to Maximus and the Rome ideal(now apparently her lover) the other(Mescal) is her son (who she likely didn't know was now a gladiator.