Yudhishthira and Krishna on the same Dharma  Chariot

Yudhishthira’s Dharma is apparently  different from Krishna’s pragmatic Dharma.
Just after the Pandavas leave for  forest exile, hearing that, the Bhojas, the Vrishnis, and the Andhakas goes to meet them one day.

Krishna suggests avenging the wrong  by acting immediately and says in a fiery speech, 'The earth shall drink the  blood of Duryodhana and Karna, of Dussasana and the wicked Sakuni! Slaying  these in battle and defeating their followers along with their royal allies, will  we all install Yudhishthira the just on the throne! The wicked deserve to be  slain! Verily, this is eternal morality – nikR^ityopacharanvadhya eva dharmaH  sanAtanaH (CE-3.13.6) 

Though Krishna  calls such action - dharmaH sanAtanaH, Yudhishthira does not approve it. He  disagrees with Krishna on Dharma, and decides  to stay in forest and incognito for 13 years in strict adherence to his  promise. Krishna has to bow before  Yudhishthira’s Dharma and leave for Dwarka. Why I use the word ‘apparently’ is  owing to this.

Though Bhima and Draupadi are  fuming, Krishna recognizes Yudhishthira’s Dharma, and it becomes clear that  Krishna only proposes immediate war to show his solidarity with Draupadi, Bhima  and others preferring war in violation of the promise of exile, but more  willing to make it a point before them that Yudhishthira’s dharma should be the  prime guiding force in the next course of action. In other words, Krishna bows before Yudhishthira’s dharma to raise the  flag of Yudhishthira’s dharma.

It would not be wrong to say, Krishna understands Yudhsihthira more than anyone else, even more than Arjuna, who seems to understand Yudhishthira only after Yudhishthira has taken a decision or stand.

On  being advised by all to perform Raajasuuya, Yudhishthira decides to take Krishna’s counsel. When Krishna  comes, he tells him, 'I have wished to perform the Rajasuya sacrifice. That  sacrifice, however, cannot be performed by one's wishing alone to perform it.  Thou knowest, O Krishna, even thing about the means by which it may be  accomplished. He alone can achieve this sacrifice in whom everything is  possible, who is worshipped everywhere and who is the king of kings. My friends  and counselors approaching me have said that I should perform that sacrifice.  But, O Krishna, in respect of that matter, thy words shall be my guide. Of counselors  some from friendship do not notice the difficulties; others from motives of  self-interest say only what is agreeable. Some again regard that which is  beneficial to themselves as worthy of adoption. Men are seen to counsel thus on  matters awaiting decision. But thou, O Krishna, art above such motives. Thou  hast conquered both desire and anger. It behoveth thee to tell me what is most  beneficial to the world."(KMG-Adi.13)

And why  Krishna wants Yudhishthira to be the ‘Centre’  is understandable from what he thinks about Yudhishthira. Advising Yudhishthira  to perform Raajasuuya only after killing Jarasandha, Krishna tells him, ‘It  hath been heard by us that in the krita age, having brought every one under  their subjection, Yauvanaswin by the abolition of all taxes, Bhagiratha by his  kind treatment to his subjects, Kartavirya by the energy of his asceticism, the  lord Bharata by his strength and valor, and Maruta by his prosperity, all these  five became emperors. But, O Yudhishthira, thou who covetest the imperial  dignity deserves it, not by one but by all these qualities, viz., victory,  protection afforded to thy people, virtue, prosperity, and  policy.(KMG-Sabha.15)’

Once, during their forest exile, the wandering Pandavas reach Prabhasa. The Yadu leaders come to visit them there. Satyaki proposes war, but Krishna politely cuts his enthusiasm short saying, ‘this bull of the Kuru race (Yudhishthira) would never accept the sovereignty of the earth, unless it were won by the prowess of his own arms. Neither for the sake of pleasure, nor from fear, nor from covetousness, would Yudhishthira ever renounce the rules of the caste - na.hy.eSa.kaamaan.na.bhayaan.na.lobhaad;yudhiSThiro.jaatu.jahyaat.sva.dharmam; nor would these two heroes, who are mighty, when mounted on a car—Bhima and Arjuna; nor the twin brothers, nor Krishna, the daughter of Drupada.(CE-3.120.22-23)’

Krishna’s respect for Yudhishthira’s svadharma is evident. Krishna also understands the ‘unique glue’ of the Pandavas and Draupadi, even more than they understand!

In  reply to Krishna Yudhishthira says, 'It is not strange that thou shouldst speak  thus, O scion of Madhu's race! but to me truth seems to be the first  consideration, above that of my sovereign power itself. But it is Krishna alone  who precisely knoweth what I am; and it is I alone who precisely know what Krishna (really) is-  kRSNas.tu.maam.veda.yathaa.vad.ekah;kRSNam.ca.veda.aham.atho.yathaa.vat. O thou  endued with valour! O scion of Madhu's race! as soon as he will perceive that  the time is come for feats of bravery, then, O most valiant of Sini's race, he  also of beautiful hair (Krishna) will defeat  Suyodhana. Let the brave men of the Dasarha race go back today. They are my patrons;  and the foremost of human beings, they have visited me here. O ye of  immeasurable strength! Never fall off from the path of virtue-  dharme.apramaadam.kuruta.aprameyaa. I shall see you again, when ye will be  happily gathered together.'(KMG-Vana.120/CE-3.120.26-28) 

Yudhsihthira’s saying – ‘Krishna alone who precisely knoweth what I am; and it is I alone who precisely know what Krishna (really) is’- makes it all the more evident that he and Krishna are the true Indra-Vishnu pair in Mahabharata.

Once, Krishna and Satyabhama visited the Pandavas in forest, and then Krishna told Yudhishthira – ‘'O king, Virtue is preferable to the winning of kingdoms; it is, in fact, practice of austerities! By you who have obeyed with truth and candor what your duty prescribed, have been won both this world and that to come! First you have studied, while performing religious duties; having acquired in a suitable way the whole science of arms, having won wealth by pursuing the methods prescribed for the military caste, you have celebrated all the time-honored sacrificial rites. You take no delight in sensual pleasures; you do not act, O lord of men, from motives of enjoyment, nor do you swerve from virtue from greed of riches; it is for this, you have been named the Virtuous King, O son of Pritha! Having won kingdoms and riches and means of enjoyment, your best delight has been charity and truth and practice of austerities, O King, and faith and meditation and forbearance and patience! (KMG- Vana.182)

Krishna respects Yudhishthira’s  Dharma, because his Dharma is in accordance to ‘svadharma’.
        The man who advises Arjuna –
  ‘shreyAnsvadharmo  viguNaH paradharmAtsvanuShThitAt.
  svadharme  nidhana.n shreyaH paradharmo bhayAvahaH -
  One's  inferior natural work is better than superior unnatural work. Death in carrying  out one's natural work is useful. Unnatural work produces too much stress.        (Gita-3.35)
       - certainly does not want to ‘change’ any  one’s svadharma, or impose his svadharma on others.