What shifts between the two uses of “thaqilta” in the poetic exchange?

Tawjīh, Serious Intent in Jest, Feigned Ignorance, Qawl bi-l-Mūjib and Iṭrād

• The verb’s gender and grammatical form
• The addressee’s identity
• The relation of “burden”: annoyance becomes generosity
• The first line’s rhyme