For all my mecha fans, I am truly sorry but unfortunately, I hate Gundam. But on a positive, I do like Char Aznable. This particular series all about him, although the title does include that it is about the chronicles of both him and Sayla. That is only because Sayla is his younger sister. The main character is Char and the plot focuses on him.
Just to be clear Char Aznable's biological name is Casval Rem Deikun also known as the Red Comet. He is the antagonist of the 1979 series but this story is the prologue to that. It explains why he works for the Principality of the Zeon which is operated by the Zabi Family (named after his father Zeon Zum Deikun).
His father was murdered which allowed a political takeover and a war to start between the confederation and the Zeons. Which resulted in the colonies to suffer in the crossfire. Within all of these dynamics, Char and Sayla were required to flee to Earth and then later adopted by Ramba Ral's father and had his name changed to Edouard Mass. The siblings had to be adopted because his mother was forced to stay behind because of Deikun's first wife was spiteful and wanted her to root in a tower until death.
Prior to even reaching Earth, Char became friends with the real Char Aznable.
The original Char resided in New Texas colony, where the Mass' stayed in between their refuge. They both became good friends. When it was known that the original Char was going into the military, Casval seized his opportunity to switch places with him. This is what promotes him to wear the headgear that he does. It is meant to shield his eyes because he has blue eyes when the original Char has dark brown. That is how many were able to tell them apart. Once Casval is able to take his place he then stands out in the Zeon military school on purpose.
By doing so he is able to gain trust by the Zeons and overshadow the Zeon heir, Garma Zabi.
Garma is not necessarily a weak character but compared to Char he is no match. This why their friendship was necessary. They had to become friends so Char does not continue to overshadow him but is able to work underneath him later on during the war so he is able to move forward with his revenge plan. Char and Garma do know each other previously when they were younger but because this is year after Char has fleed to Earth and later pronounced dead Garma is unaware that Char is Casval.
Now I did leave out a few details purposely because you have to work this series and the 1979 series to better understand the character of Char and why he is so important to the Gundam franchise. This series is only an OVA with hour-long episodes. I preferred this series out of all the Gundams I have currently watched. Just because Char is a mysterious character. Along with the fact that in the 1979 series it is unknown if he died or survived at the end of the war. But it is later confirmed in a later series, Mobile Suit Zeta Gundam (1985) that he did survive.
Lastly, did Lalah deserve to be with Char? Yes? When you decide to view this series and understand how Char met Lalah and then see how they interact in Gundam 1979 and notice how Amaro has a connection with Lalah that is not explained. It is kind of sad how Lalah was taken away from Char when he has already lost so much. He gave up his sister, both his parents have died. This man is harboring so much pain and seeks revenge. Piloting a mobile suit may be his only way to release this pain and anger.