Some listen, the Pharaoh says sorry yet still hardens his heart...
Hail is in challenge to Nut, Locusts to Serapia and darkness challenges the mighty Ra...The hail continued until Pharaoh humbly asked for intercession v28 - yet once again retracted his change of heart. Locusts...Pharaohs servants beg him lest Egypt be destroyed, Pharaoh tries to negotiate just the men leaving, yet Moses states in 10:9 All of us are going! In 10:16-17 Pharaoh says sorry, prays the locusts be gone, yet again hardens his heart once all is normal again. Bring on the darkness, again negotiations are unsuccessful and on v29 of chap 10 Moses states negotiations are done after Pharaoh threatens his life. At this point both Egypt and Israel are growing to know Jehovah, they are seeing the power in the story of hard things. The Israelites, Moses and Aaron are now ready for the the final plague.

Jehovah has shown very clearly that He has all the power - over all of earthly things - He is mightier than Pharaoh, the magicians, the Egyptian Gods including the mighty Ra...remember this is a lesson in changes and growth and opportunities, none of which Pharaoh took. He is about to know Jehovah very well.