I personally do not want Ramos to play at Sevilla, because at least Ramos will play against Real Madrid later. Therefore, maybe Ramos will tarnish his loyalty to Real Madrid, and a case like this maybe remind me when Lampard played at Manchester City at the time. What's worse, Lampard made a goal when Lampard playing for Manchester City against Chelsea at that time.
Real Madrid fans may not expect Ramos to play in other teams in La Liga. But Ramos may choose Sevilla because it is the option to continue his career now. We know Ramos was a Sevilla player, it will be a great history that he returned to Sevilla again after he left Sevilla many years ago. If he decided to retire in Sevilla, he will be a legend both in Sevilla and Real Madrid.
Sure, when he plays for Sevilla, he will show his loyalty for Sevilla. Ramos has no responsibility to show hos loyalty to Real Madrid because he is no longer Real Madrid player. I'm sure every one will understand it although it seems a bit unusual when Ramos played against Real Madrid players. He probably does what Lampard ever did to Chelsea.
Although yea, at least I also really appreciate Ramos, because Ramos is not tempted by big money because Ramos also rejected an offer from a club in the Saudi Pro League. But yes, that doesn't mean Ramos has to be Real Madrid enemy in La Liga.
Ramos may feel uninterested with Saudi pro league. It is normal, each player may have a different priority and preference for his career. Joining Sevilla seems not a bad idea, he returned to his previous club. Sure, he will play against Real Madrid this season. He must be professional, it won't be a problem for him.