Perceptions are an interesting concept. What we perceive isn’t always what is, and two people can have very different perceptions of the same person.
I think a good example of this is the Merlin episode 5×03, “The Deathsong of Uther Pendragon”. During this episode, Arthur finds a magic horn that lets him talk to his dead father, Uther, but accidentally releases his father’s ghost onto Camelot.
Or at least that’s what Gauis says the problem is. But I don’t think that was Uther’s ghost.
When Uther is released, he immediately starts to attack everything Arthur’s changed since he inherited the crown in season four – first the round table, then one of the commoner knights, and finally Queen Guinevere, who wasn’t born royal and therefore Uther didn’t approve of the marriage. While it’s Merlin who eventually points out the trend, it actually started with Arthur during a meeting at the round table – which stands for everything Arthur’s changed since his reign.
During Uther’s attack, he is very characteristic – paranoid, unnecessarily violent, and set in his ways. But during the attack, he does something very uncharacteristic – he decides that the kingdom is worth Arthur’s life.
No, there is no point in the previous episodes that I can point to and say that he says the opposite. But throughout the series Uther is willing to do pretty much anything for his son – acting even more irrational than usual. Would Uther actually kill Arthur, even for the sake of the kingdom?
What I think is more likely is that Uther is a projection of Arthur’s perception of him. After meeting his father using the horn, Arthur begins thinking about him during the round table meeting, and triggers the ghost. He believes that despite doing what’s best for his kingdom, Uther would be disappointed.
Further proof is when Uther is alone with Merlin. He completely changes to what Merlin thinks him as – cruel and unrelenting. While, again, not completely out of previous characterization, the change is suspicious.
The most obvious thing is after Merlin reveals his magic to the “ghost”, Uther doesn’t immediately tell Arthur about it. Instead, when Arthur arrives, his focuses shifts back to him and his reign of Camelot. It’s only when Merlin arrives that Uther remembers Merlin’s magic, and before he can say anything Arthur sends him back with the horn. It’s almost as if that since Arthur didn’t know, Uther couldn’t know. It was only with the arrival of Merlin, and his memory of the previous encountered, that Uther brings it up.