What is the ruling on a maternal aunt kissing her brother's son, embracing him, uncovering her hair, and so on, if they are both young adults of the same age?

It is permissible for a maternal aunt to kiss and embrace her nephew upon his return from a journey or similar occasion, provided that there is no suspicion (ريبة), safety from temptation (فتنة), and no physical contact of private parts. It is also permissible for her to uncover her hair, neck, and hands in front of him. However, if suspicion or lust arises, then even a mere glance becomes forbidden, for "looking with lust is absolutely forbidden towards anyone looked at—whether a mahram or not—other than one's wife or female slave."