Mischievous, prankish, teasing, disagreeable but in a good way.
Cantankerous, stubborn, disagreeable.
Excessively sweet in action or disposition, especially if romantic or sentimental to the point of ridiculousness; sickly sweet, syrupy.
Resembling granulated sugar; saccharoid.
Of or relating to saccharin (“a white, crystalline powder, C₇H₅NO₃S, used as an artificial sweetener in food products”).
Sentimentalism.