Chinese Emperors since Qin Dynasty (~2200 years ago) had a specific self claim to call himself, any other people couldn't use the claim.
The shell bone script of character I (Emperor self claim) is
The bronze script of the character is
Similar to shell bone script.
The small seal script of the character is
The left is boat, the right bottom are two hands, which are same as the older scripts. However, the right top is character Fire (Post 26), which is different from the older scripts. Dictionary of Pictography thinks that this was written by mistakenly. I think that it is possible, the emperor is the person who holds a torch because before small seal script, the character was not the emperor self claim term, but from small seal script when was Qin Dynasty, the character was used as emperor self claim, he was of course not the boatman anymore but sit in the boat as commander. The torch is the sign of him to guide other boats to follow. So this change is reasonable.
The clerical script of the character is
The left is character Moon (Post 53), which is a mistake because character Boat is similar to character Moon. The right one is character Close (Post 358), which was simplified by careless. Because people who created clerical script wanted to write faster, didn't pay attention to the pictography at all. We see many characters being changed unreasonably.
The song typeface of the character is
Same as the clerical script.
Its Pinyin is Zhen4.