In Dylan Thomas' "Do Not Go Gentle Into That Good Night" was written about his father. His father was a strong military man for most of his life. It was not until he reached his eighties that he became weak and blind. As you can imagine, this was hard for Dylan Thomas to witness. His poem is urging his father not to give up so easily.
“Do not go gentle into that good night.”
This line means do not go easily
He repeats this line and urges his father to fight in each stanza.
In the last stanza he says:
“And so my father you are nearing death—yell at me, scream at me, cry out; to see you do that would be a blessing for me and I beg you to show me that militant man you once were: “Do not go gentle . . . . ”
He is longing for his father to be the strong man that he once was again. He is telling his audience that he wants his father to die as he lived, a strong man.
The last stanza indicates that he wants his father, who is dying, to not go without a fight, without clinging fiercely to life until the very end. He asked his father to "Curse, bless, me now with your fierce tears, I pray." This indicates he wants his father there, lucid, blessing and cursing him "fiercely" until the very end. He wants his father to be similarly intense with death, to "rage, rage" against it.
From these lines we can infer that he cared deeply about his father. First of all, he felt strongly enough about his father to write a poem about his struggle against death. Secondly, he respected his father and wanted him to have a proud, fighting end. Thirdly, he mentiioned himself at the death bed, and that he wanted his father's love and attention until the very end (the blessings and cursings). This indicates a very close relationship, and Thomas himself seems to rage against death, which indicates he is upset that it is taking his father away.