Those nearest to him;
Unlike a lot of characters in some RPG games, the family and background from which the main characters come from is quite important. These relationships play an important role in determining the personalities of each individual character. Ziggy is no different. Family seems to be something that Ziggy values a lot, however, it never seems to work out for him.
Original Family
Father
Although the main three episodes of the game never give out any details about Ziggy's parents or his life when he was very young, his cell phone game, Pied Piper sheds some light on this subject. Jan's father whose name is unknown was also a policeman. He worked very hard for his family, but he was working almost all the time. Young Jan doesn't carry any substantial memories of him. In fact, by the time we meet him in Episode I, it's likely that he doesn't even remember anything about him, nor what he looks like. However, he does seem to have psychological effects left over from his father. He at around the age of 30 on the job when he was still very young. At the time when he died, he was also a captain. Jan later decides to become a police officer, due to his admiration for his father.
MotherIngrid had a very hard time after the death of her husband. By the time Jan was a young teenager or so, she is somehow missing from his life. The game doesn't actually state an age, but it mentions him as being a "young man", but not an adult yet. The game also doesn't explain what happened to her. Her sprite just vanishes. My educated guess is that she fell into a deep depression and either became very ill, or she killed herself, not able to live with the grief anymore. The little bit that is told to us, is that she was very depressed and she cried a lot. This left an impact on him, and can be seen with his interaction with Sharon. Perhaps this even plays a part in wanting to protect MOMO and Juli.
Adoptive Father
Sean McCallum was a friend of Jan's father, and he seemed to look up to him a lot. He calls him something akin to the english "uncle". But it doesn't imply that they are related. The game just states that Sean is Jan's father figure after his real parents were no longer around. He often gives him advice, and tries to remind him of what is really important. He cares for Jan, and doesn't want him to be like his father, constantly putting duty first. Uncle Sean is eventually arrested on charges of terrorism along with Jan and the rest of his team. He is replaced by an underling of Dimitri Yuriev named Ernest Lewis. Later, while trying to escape from a police detention center, Jan comes across him in a room, badly injured. He manages to tell Jan how proud he is, and that he doesn't have any regrets. Jan holds onto him shaken, as he tells him and the others to leave. Then, he dies in Jan's arms.
Wife and Stepson
Sharon and Joaquin Rozas
Jan first meets Sharon Rozas after the first incident involving Voyager. She is one of the head nurses at the Archon hospital. Sharon was married to a police officer before. However, he died during a prison riot. Sharon seems to be a very strong person, but she admits to living in an "ashen world" because of the loss of her husband. When Jan learns of this, he finds himself attached them. In one hand it does appear that he does like them. I think, however, the main reason for him to choose to be involved with them is because their situation mirrors his own. Joaquin tells Jan that he sometimes sees his mother cry. This probably reminds him of his own mother. Not wanting the same fate to befall them, he decides to marry Sharon. Joaquin is very happy to have a new father. For the short time that they are together, he does whatever he can for them. He even buys Joaquin a cybernetic dog that he had been wanting. Sharon is quite diligent and she works hard, along with her new husband to help solve the case. However, after deciding to go to the Pilgrimage Council to find her own answers, she and Joaquin are killed by Voyager right in front of Jan's eyes.
Adoptive Family
MOMO and Juli Mizrahi
When first meeting Juli Mizrahi, he is a bit surprised how Juli seems to regard the 100-series Realian that is registered as her legal daughter. However, since he knows very well that he has no right to question her motives, he doesn't bring it up until later. Almost immediately, him and MOMO form a bond which can only be described as that of father and daughter. She gives Ziggy his nickname, and this brings him memories of Joaquin. During the course of the story, the two grow very close, and MOMO can usually be seen with Ziggy somewhere nearby. Ziggy constantly insists that MOMO is very useful, and MOMO quote obviously admires him. Before MOMO's analysis, Ziggy finally talks to Juli and asks if she would consider MOMO to be a second daughter instead of a copy of Sakura. When MOMO cuts off her neural network in order to protect the Y-Data, Ziggy and Juli act akin to parents whose daughter is in trouble. At the end of Episode II, Juli in turn, asks Ziggy to go through life extension for MOMOs sake, and for hers as well.
By the time we see Juli in Episode III, she has become a different person, thanks to MOMO. Along with Ziggy, her heart was opened by MOMO's caring and warm personality. Although there is next to no interaction between Ziggy and Juli in Episode III, she does thank him for everything he has done sofar while on the Elsa. By the end of the story, Jr asks Ziggy if he would look after Juli and MOMO for him. Ziggy tells him not to worry. Ziggy stays with Juli and MOMO on the Dammerung, to help reconstruct a new network.
In many ways, I think that Juli is very much like Sharon, not just because they share similar professions. Both Juli and Sharon's stories both involve the loss of someone close to them, and thus, they fell into a sort of despair. Both of them however, do whatever they can to keep going. Sharon continues for her son, and Juli wants to get to the bottom of her late husband's research.
I would like to think that Ziggy and Juli would end up together. However, Ziggy still has some unresolved issues. I don't think he would be willing, at least without some time, to allow himself to endanger another family. He doesn't know how long he will continue to live. I think that there is a sort of love there, maybe not in the romantic sense, but it could certainly grow with time and assurance. If anything, I think that he would do everything he can to be a good fatherly figure toward MOMO.
Ziggy's ending is a truly happy one, I think. He is given back what he had lost, and another chance to right all of his wrongs of the past. However, I think by the end, he is willing to put this past, and his heavy losses behind him.