In Bram Stoker's Dracula, Lucy Westenra receives four blood transfusions from four different men: First from her fiancé, Arthur Holmwood, and later from Dr. Seward, Van Helsing, and Quincey Morris.
Arthur makes a comment about feeling closer to Lucy since the operation and later remarks that he feels as if the transfusion has made her truly his wife. For this reason the others decide that he should never know about the other transfusions.
When it was all over, we were standing beside Arthur, who, poor fellow, was speaking of his part in the operation where his blood had been transfused to his Lucy's veins; I could see Van Helsing's face grow white and purple in turns. Arthur was saying that he felt since then as if they two had been really married, and that she was his wife in sight of God. None of us said a word of the other operations, and none of us ever shall.
— Chapter XIII, Dr. Seward's Diary
And again, some paragraphs later, Van Helsing and Dr. Seward talk about Arthur's remark and the implications (of which Arthur is and should remain blissfully unaware).
'Well, for the life of me, Professor,' I said, 'I can't see anything to laugh at in all that. Why, your explanation makes it a harder puzzle than before. But even if the burial service was comic, what about poor Art and his trouble? Why, his heart was simply breaking.'
'Just so. Said he not that the transfusion of his blood to her veins had made her truly his bride?'
'Yes, and it was a sweet and comforting idea for him.'
'Quite so. But there was a difficulty, friend John. If so that, then what about the others? Ho, ho! Then this sweet maid is a polyandrist, and me, with my poor wife dead to me, but alive by Church's law, though no wits, all gone—even I, who am faithful husband to this now-no-wife, am bigamist.'
— Chapter XIII, Dr. Seward's Diary
And earlier, after Dr. Seward gives blood, Van Helsing said this to him:
'Mind, nothing must be said of this. If our young lover should turn up unexpected, as before, no word to him. It would at once frighten him and enjealous him, too. There must be none. So!'
— Chapter X, Dr. Seward's Diary
However, later on, Dr. Seward, Van Helsing, Arthur, Quincey, Jonathan Harker, and Mina Harker all gather their collective journals and notes and read them so that they may come up with a plan for how to deal with Count Dracula.
We know that these collected journals include Dr. Seward's phonograph journal, transcribed by Mina Harker, wherein he discusses the entire treatment of Lucy, because in Chapter XVII, Mina convinces him to let her hear and transcribe his entire journal, despite his initial reluctance.
By this time my mind was made up that the diary of a doctor who attended Lucy might have something to add to the sum of our knowledge of that terrible Being, and I said boldly:
'Then, Dr Seward, you had better let me copy it out for you on my typewriter.' He grew to a positively deathly pallor as he said:
'No! no! no! For all the world, I wouldn't let you know that terrible story!'
'You do not know me,' I said. 'When you have read those papers—my own diary and my husband's also, which I have typed—you will know me better. I have not faltered in giving every thought of my own heart in this cause; but, of course, you do not know me—yet; and I must not expect you to trust me so far.'
He is certainly a man of noble nature; poor dear Lucy was right about him. He stood up and opened a large drawer, in which were arranged in order a number of hollow cylinders of metal covered with dark wax, and said:
'You are quite right. I did not trust you because I did not know you. But I know you now; and let me say that I should have known you long ago. I know that Lucy told you of me; she told me of you too. May I make the only atonement in my power? Take the cylinders and hear them—the first half-dozen of them are personal to me, and they will not horrify you; then you will know me better.'
— Chapter XVII, Mina Harker's journal
'Oh no, not distressed me,' she replied, 'but I have been more touched than I can say by your grief. That is a wonderful machine, but it is cruelly true. It told me, in its very tone, the anguish of your heart. It was like a soul crying out to almighty God. No one must hear them spoken ever again! See, I have tried to be useful. I have copied out the words on my typewriter, and none other need now hear your heart beat, as I did.'
'No one need ever know, shall ever know,' I said in a low voice. She laid her hand on mine and said very gravely:
'Ah, but they must!'
'Must! But why?' I asked.
'Because it is a part of the terrible story, a part of poor dear Lucy's death and all that led to it; because in the struggle which we have all before us to rid the earth of this terrible monster we must have all the knowledge and all the help which we can get. I think that the cylinders which you gave me contained more than you intended me to know; but I can see that there are in your record many lights to this dark mystery. You will let me help, will you not? I know all up to a certain point; and I see already, though your diary only took me to 7 September, how poor Lucy was beset, and how her terrible doom was being wrought out. Jonathan and I have been working day and night since Professor Van Helsing saw us. He is gone to Whitby to get more information, and he will be here tomorrow to help us. We need have no secrets among us; working together and with absolute trust, we can surely be stronger than if some of us were in the dark.' She looked at me so appealingly, and at the same time manifested such courage and resolution in her bearing, that I gave in at once to her wishes. 'You shall,' I said, 'do as you like in the matter. God forgive me if I do wrong! There are terrible things yet to learn of; but if you have so far travelled on the road to poor Lucy's death, you will not be content, I know, to remain in the dark. Nay, the end—the very end—may give you a gleam of peace. Come, there is dinner. We must keep one another strong for what is before us; we have a cruel and dreadful task. When you have eaten you shall learn the rest, and I shall answer any questions you ask—if there be anything which you do not understand, thought it was apparent to us who were present.'
— Chapter XVII, Dr. Seward's diary
I read this to mean that Dr. Seward agrees that it is best if all of them learn the full details of what happened to Lucy, even though that means revealing the three other transfusions to others, including Arthur.
And it seems clear to me that the only one who is ever kept in the dark about anything beyond this point is Mina. As far as I can tell, there's no mention of Arthur not reading all the journals, or the journals being redacted for him.
And yet, as far as I can recall, we also never hear of any reaction from him to learning about the other transfusions, which struck me as odd given how much was made of it. Did I miss it, or was it truly glossed over?