Courtly and Romantic: The poem is steeped in the conventions of courtly romance, evident in its elegant language, idealized characters, and focus on chivalry and courtly love. The tone is often lyrical and even sentimental, as seen in descriptions of nature and the knights' noble deeds.
Serious and Solemn: Despite its romantic aspects, the poem grapples with serious themes of mortality, sin, and redemption. The Green Knight's challenge and Gawain's subsequent journey are infused with a sense of foreboding and existential dread. The poem's ending, with its focus on Gawain's confession and acceptance of his flaws, carries a somber and reflective tone.
Humorous and Playful: While serious in its underlying themes, the poem also displays a playful and humorous side. The Green Knight's outlandish appearance and behavior, as well as Gawain's occasional lapses in judgment, add a lighthearted element to the narrative.
Ironical and Ambiguous: The poem is rich in irony and ambiguity. Gawain's noble intentions are often overshadowed by his human flaws and weaknesses. The Green Knight's true identity and motivations remain shrouded in mystery, creating a sense of uncertainty and unsettling the reader's assumptions.
Didactic and Moralistic: The poem offers a strong moral message, emphasizing the importance of honesty, courage, and humility. Gawain's journey is ultimately a journey of self-discovery, forcing him to confront his own imperfections and ultimately learn from them.
Overall, the tone of "Sir Gawain and the Green Knight" is a complex blend of courtly romance, seriousness, humor, irony, and moral instruction. This complex interplay of tones contributes to the poem's enduring power and relevance.