The theme of love is explored through the forbidden romance of Jake and Rose. Their romance is akin to Romeo and Juliet due that Jake is a dragon and Rose is a dragon slayer. At first neither were aware of each other relationship to the Magical World but when they found out about that at the end of Season One their romance stood in jeopardy.
In Season Two the two sought to rebuilt their romance by making use of the Dream Charms, which enabled them to travel to the Dream Realm where they could have dream dates (literally!) and where they could express their feelings without fear. Their romance was brutally ended when Rose wished for the destruction of the Huntsclan. Due to the Huntsman desire to wipe out all magical creatures by using of thirteen mystical artifacts called Aztec Skulls the young blonde had to stop his plans by self-sacrifice. Fortunately Jake was capable of using one of the skulls to wish that Rose was never taken by the Huntsclan, even though it caused a AU Rose to travel to Hong Kong.
The friendship theme is explored through the trio of Jake, Spud and Trixie. At first Jake's dragon duties put a hold on his social life often forcing him to not be capable of spending time with his friends. The relationship between Jake and his friends is threatned when Professor Rotwood nearly exposes magic by using the Taranushi Chalice, which was a trophy for the school talent show.
Gramps forced Jake to enter the talent show and compete with Spud so that he could win the chalice and stop the exposure of the magical world. In the end Jake choose friendship and left the talent show. Fortunately Spud gave him the trophy though Jake lost it anyway.
Their friendship is truly put in test when Trixie and Spud find out that Jake is a dragon. After selling him accidentaly to Rotwood, the two of them found out through the photos on Jake's PC that he was a dragon. They were capable of saving him in time.
The racism theme is explored in two ways both from the non-magical as well the magical perspective. From the magical perspective there's the Dark Dragon . A powerful member of the race meant to protect all magical creatures the Dark Dragon is feared through out the Magical Community due to his vast dark powers. The Dark Dragon believes that magical creatures- dragons more especifically- are inherently superior to the "inferior humans". And as such magical creatures should unite and overthrown the humans so they could take back their rightful place as rulers of the Earth.
In the non-magical perspective we have the Huntsclan, an ancient organization whose goal is to rid the Earth of all magical creatures. In the Huntsclan perspective magical creatures are unnatural beasts who pollute the Earth. Thus its the duty of the Huntsclan to destroy them.
Strongly tied with racism the idea of genocide is not directly addressed though its clearly visible in the first half of Season Two. The leader of the huntsclan, the Huntsman desires to destroy the "foul magical creatures that pollute this planet" and as such snatch a master plan to accomplish that.
The Aztec Skulls were thirteen mystical artifacs that had the power to warp reality and thus grant any wish, even though it could grant one wish that was irreversible. Fortunately Rose was capable of stop the Huntsman before he finished his wish.